Threads about hard warm starts / low compression
02-27-2011, 11:27 AM
#1
He's as bad as Can
Thread Starter
Threads about hard warm starts / low compression
Is it just me or have threads on this issue increased over the last six months? I am beginning to have doubts about long term ownership of this car.
I am on my 2nd engine and it just failed a compression test, I am also having warm starting issues. I put about 40,000 miles on the 2nd engine pre-mixed and ran 5W-30 Royal Purple ( I don't wish to get into an oil debate) I at 153,000 miles I am on my own again. I was messaging an engine builder and he said 40,000-50,000 miles on a rebuilt wasn't that bad. That when re-using rotor housings one needs to take into account that its a wear item and whatever miles it had on it when it was taken apart should be added to whatever you put on it. Weather its uneven APEX seal wear do to no 3rd OMP jet or housing wear these engines just loose compression faster than piston cars.
This made sense to me, that the only way to expect 100,000 miles from a rebuilt is if it used NEW housings. That brings the total cost of a rebuilt to over $5,000. So the people installing engines that reuse housings are not going to reach 100K no matter how they take care of it? Dropping $4,000 every 50,000 miles is something I don't wish to do. Does anyone know if the rebuilt engines the dealerships use come with new housings?
I guess what I am asking here is for other opinions about rebuilt longevity and has anyone else also noticed a increase in compression related threads. Since the majority of RX-8 on the road are 2004 & 2005's engines failure threads could continue to grow and further tarnish the cars rep.
I am on my 2nd engine and it just failed a compression test, I am also having warm starting issues. I put about 40,000 miles on the 2nd engine pre-mixed and ran 5W-30 Royal Purple ( I don't wish to get into an oil debate) I at 153,000 miles I am on my own again. I was messaging an engine builder and he said 40,000-50,000 miles on a rebuilt wasn't that bad. That when re-using rotor housings one needs to take into account that its a wear item and whatever miles it had on it when it was taken apart should be added to whatever you put on it. Weather its uneven APEX seal wear do to no 3rd OMP jet or housing wear these engines just loose compression faster than piston cars.
This made sense to me, that the only way to expect 100,000 miles from a rebuilt is if it used NEW housings. That brings the total cost of a rebuilt to over $5,000. So the people installing engines that reuse housings are not going to reach 100K no matter how they take care of it? Dropping $4,000 every 50,000 miles is something I don't wish to do. Does anyone know if the rebuilt engines the dealerships use come with new housings?
I guess what I am asking here is for other opinions about rebuilt longevity and has anyone else also noticed a increase in compression related threads. Since the majority of RX-8 on the road are 2004 & 2005's engines failure threads could continue to grow and further tarnish the cars rep.
Last edited by expo1; 02-27-2011 at 11:32 AM.
02-27-2011, 01:50 PM
#2
kevin@rotaryresurrection
iTrader: (3)
Join Date: Feb 2005
Location: east of Knoxville, TN
Posts: 1,415
Likes: 0
Received 57 Likes
on
35 Posts
The real problem here is the cost of parts from mazda. IF the parts cost were more reasonable it wouldn't be as big of a deal to go through the engine every 50-75k. Mazda doesnt really support it's owner and enthusiast base very well IMO, as they are CONSTANTLY jacking up prices and making parts less available. Earlier this year mazda cut off a significant parts supply line to many resellers, forcing them to utilize the dealership network to obtain parts (at prices 10-20% higher). Every time I call to order oem parts the prices have usually gone up at least 5%.
Also you are just now starting to hear of a lot more engine problems because even on 04 and 05 models, a lot of them were second cars or weekend cruisers and just now getting to the 50k+ mile range. All of those guys who've commented for years about how reliable their 8 has been are going to start riding in the same boat as the high mileage guys pretty soon.
The mazda remans use a mix of new and used parts. I'd go out on a limb and say that >50% of the time they use new rotor housings. But we have no proof of that, and there are never any "build sheets" accompanying mazda reman engines. You never know "what you have" with those, you are rolling the dice that you will get more new than used parts. Expect irons, rotors, and e-shafts to be used; expect bearings and rotor seals to be new, and rotor housings could go either way just depending on what they had on hand from the core reclamation process at the time. There are also times when the reman program runs low/out of "reusable" core parts and so they will build from all new parts for a while until enough used parts are obtained to start building from again. But again unfortunately there is no way to insist on getting one of these "new part" remans even though you know they exist...you simply take whatever shows up at the dealership where you order the reman.
If you see a reman with silver paint on the rotor housings, they are used. IF they are dull bare aluminum then they are new. The front covers almost always get reused and they are also aluminum like the rotor housings, so you can compare the silver paint on the front cover to the finish of the rotor housings to figure out if you've got new or used housings.
Another problem with remans is not the parts used, but how they are assembled. For years the rx7 remans have been of really questionable quality. I've taken apart tens of them myself. They always have a TON of sealant globbed all over the oil pan and also in other places where the factory never even called for sealant...such as on the front snout of the e-shaft where the gears and such get installed. This excess sealant can flake off of the pan and other areas and actually clog the oil pan pickup strainer. They also tend to be way off on their side seal clearances on the rx7 engines (I havent taken apart enough rx8 remans to judge them yet). Sometimes they do reuse a component that obviously should not have been. I've seen them reuse one iron with a streetport while using others with stock ports. I've seen them reuse rotors with previous significant apex seal slot damage. Or rotor housings with previous apex seal damage. I even once took apart a 93-95 rx7 engine (which would come stock with 9.0:1 compression rotors) that had blown apex seals on the front rotor (fairly unusual, usually the rear rotor blows first). As it turns out the reman plant had used a higher compression 9.7:1 rotor from an 89-91 non turbo in the front, and the correct 9.0:1 rotor in the rear.
Perhaps now that mazda handles its reman program directly with their own facility (as opposed to the third party facilities they've always used in the past) reman quality will go up.
Rotary rebuilders and knowledgeable enthusiasts have always known and stated that "new rotor housing" rebuilds are the best way to get that "new engine feel" and optimal engine compression and longevity. Anytime you reuse a part that has any wear, especially any significant wear, you introduce a compromise into the engine that will likely lower compression. So why do it? COST. Not many people can afford the 4-5 grand to "do it right" by replacing every single wear part in the engine.
The rebuilders have a delicate balancing act to perform, trying to keep costs in check so customers will buy engines from them instead of going used or just selling the car, while also putting enough good/new parts into the engine to make it run well, reliable and retain some longevity. You can't pull new parts out of your *** so someone somewhere is going to have to pay for them. Some builders err more on the side of caution and put in more new parts (while charging the customers more) and others such as myself charge less and reuse as much as is feasible depending on the situation...still offering the customer the ability to choose what parts are reused or replaced (and thus what they pay). However the negative effect of operating in this manner is that, given the option, the customer will almost always choose the lower cost option, but in their mind they are still expecting a near perfect result that would normally accompany a more expensive build.
This "balancing act" is made more difficult by the customers who have no idea of the actual cost of these parts, or how a rotary engine is composed to begin with. Sometimes they will come to you talking a big game about "using all new parts" and "doing it right" but when you quote them several thousand dollars, they backpedal quickly. Some think that is money the builder is making, when in reality mazda sets the part prices and since there is a very limited aftermarket offering for optional seals and components, there aren't many ways to lower those costs. It's money mazda is making, not the builder, and that's what most people don't understand. Most builders make a few hundred dollars for their labor, equipment, costs, and liability (in offering warranty) on an engine build, regardless of how many parts are reused or replaced with new.
On the other hand other customers just want to "make it run again" and are willing to take many shortcuts and compromises for a fast turnaround and a cheap rebuild price. They are often looking to get the car running so they can sell it. Sometimes these types even misrepresent the nature of the engine rebuild when they sell the car, and the new buyer later finds out that it was a basic build with many reused parts, and the new buyer blames the builder for whatever reason.
CLIFFS: New OEM mazda parts are quite expensive, and thus the cost of owning these cars is higher than it should be.
Mazda remans often receive more new parts than private builds, but have historically been put together more poorly than private builds.
Non-mazda rebuilders put more care and precision into their one-off builds, but are often forced to reuse more parts in order to keep costs in check. Each option has it's pros and cons.
Mazda remans are often useful for those who have a grenaded core without many reusable parts at all; you can buy the mazda reman block for the parts contained therein, tear it down and perform your own porting or other custom bits, then assemble it with more care and precision than mazda.
Also you are just now starting to hear of a lot more engine problems because even on 04 and 05 models, a lot of them were second cars or weekend cruisers and just now getting to the 50k+ mile range. All of those guys who've commented for years about how reliable their 8 has been are going to start riding in the same boat as the high mileage guys pretty soon.
The mazda remans use a mix of new and used parts. I'd go out on a limb and say that >50% of the time they use new rotor housings. But we have no proof of that, and there are never any "build sheets" accompanying mazda reman engines. You never know "what you have" with those, you are rolling the dice that you will get more new than used parts. Expect irons, rotors, and e-shafts to be used; expect bearings and rotor seals to be new, and rotor housings could go either way just depending on what they had on hand from the core reclamation process at the time. There are also times when the reman program runs low/out of "reusable" core parts and so they will build from all new parts for a while until enough used parts are obtained to start building from again. But again unfortunately there is no way to insist on getting one of these "new part" remans even though you know they exist...you simply take whatever shows up at the dealership where you order the reman.
If you see a reman with silver paint on the rotor housings, they are used. IF they are dull bare aluminum then they are new. The front covers almost always get reused and they are also aluminum like the rotor housings, so you can compare the silver paint on the front cover to the finish of the rotor housings to figure out if you've got new or used housings.
Another problem with remans is not the parts used, but how they are assembled. For years the rx7 remans have been of really questionable quality. I've taken apart tens of them myself. They always have a TON of sealant globbed all over the oil pan and also in other places where the factory never even called for sealant...such as on the front snout of the e-shaft where the gears and such get installed. This excess sealant can flake off of the pan and other areas and actually clog the oil pan pickup strainer. They also tend to be way off on their side seal clearances on the rx7 engines (I havent taken apart enough rx8 remans to judge them yet). Sometimes they do reuse a component that obviously should not have been. I've seen them reuse one iron with a streetport while using others with stock ports. I've seen them reuse rotors with previous significant apex seal slot damage. Or rotor housings with previous apex seal damage. I even once took apart a 93-95 rx7 engine (which would come stock with 9.0:1 compression rotors) that had blown apex seals on the front rotor (fairly unusual, usually the rear rotor blows first). As it turns out the reman plant had used a higher compression 9.7:1 rotor from an 89-91 non turbo in the front, and the correct 9.0:1 rotor in the rear.
Perhaps now that mazda handles its reman program directly with their own facility (as opposed to the third party facilities they've always used in the past) reman quality will go up.
Rotary rebuilders and knowledgeable enthusiasts have always known and stated that "new rotor housing" rebuilds are the best way to get that "new engine feel" and optimal engine compression and longevity. Anytime you reuse a part that has any wear, especially any significant wear, you introduce a compromise into the engine that will likely lower compression. So why do it? COST. Not many people can afford the 4-5 grand to "do it right" by replacing every single wear part in the engine.
The rebuilders have a delicate balancing act to perform, trying to keep costs in check so customers will buy engines from them instead of going used or just selling the car, while also putting enough good/new parts into the engine to make it run well, reliable and retain some longevity. You can't pull new parts out of your *** so someone somewhere is going to have to pay for them. Some builders err more on the side of caution and put in more new parts (while charging the customers more) and others such as myself charge less and reuse as much as is feasible depending on the situation...still offering the customer the ability to choose what parts are reused or replaced (and thus what they pay). However the negative effect of operating in this manner is that, given the option, the customer will almost always choose the lower cost option, but in their mind they are still expecting a near perfect result that would normally accompany a more expensive build.
This "balancing act" is made more difficult by the customers who have no idea of the actual cost of these parts, or how a rotary engine is composed to begin with. Sometimes they will come to you talking a big game about "using all new parts" and "doing it right" but when you quote them several thousand dollars, they backpedal quickly. Some think that is money the builder is making, when in reality mazda sets the part prices and since there is a very limited aftermarket offering for optional seals and components, there aren't many ways to lower those costs. It's money mazda is making, not the builder, and that's what most people don't understand. Most builders make a few hundred dollars for their labor, equipment, costs, and liability (in offering warranty) on an engine build, regardless of how many parts are reused or replaced with new.
On the other hand other customers just want to "make it run again" and are willing to take many shortcuts and compromises for a fast turnaround and a cheap rebuild price. They are often looking to get the car running so they can sell it. Sometimes these types even misrepresent the nature of the engine rebuild when they sell the car, and the new buyer later finds out that it was a basic build with many reused parts, and the new buyer blames the builder for whatever reason.
CLIFFS: New OEM mazda parts are quite expensive, and thus the cost of owning these cars is higher than it should be.
Mazda remans often receive more new parts than private builds, but have historically been put together more poorly than private builds.
Non-mazda rebuilders put more care and precision into their one-off builds, but are often forced to reuse more parts in order to keep costs in check. Each option has it's pros and cons.
Mazda remans are often useful for those who have a grenaded core without many reusable parts at all; you can buy the mazda reman block for the parts contained therein, tear it down and perform your own porting or other custom bits, then assemble it with more care and precision than mazda.
02-27-2011, 01:57 PM
#3
kevin@rotaryresurrection
iTrader: (3)
Join Date: Feb 2005
Location: east of Knoxville, TN
Posts: 1,415
Likes: 0
Received 57 Likes
on
35 Posts
Also another point I wanted to make. So much is made of mileage and reliability of these cars. IT wasn't that long ago (in terms of design and engineering), about 30-35 years ago, that cars were expected to last 75, maybe 100k miles and then they had served their purpose and were considered worn out.
These days if a car can't go 200k miles on all original drivetrain components, while getting nothing but fuel and oil changes every 5k miles, while getting 27mpg, while making at least 225hp, with a purchase price of under 20k new, then it is regarded by the public as an overpriced, unreliable, slow, inefficient piece of ****. I think some among us need to take a second look at our expectations. You can't always have your cake and eat it too.
These days if a car can't go 200k miles on all original drivetrain components, while getting nothing but fuel and oil changes every 5k miles, while getting 27mpg, while making at least 225hp, with a purchase price of under 20k new, then it is regarded by the public as an overpriced, unreliable, slow, inefficient piece of ****. I think some among us need to take a second look at our expectations. You can't always have your cake and eat it too.
02-27-2011, 02:15 PM
#5
He's as bad as Can
Thread Starter
One other thing, can you tell from the compression test if the cause of the low compression was the housings or the APEX seals? Mine were fairly consistent numbers. If it was an APEX would at least a few rotor faces have a good number?
Rotor #1 =>5.6, 5.5, 5.5 @ RPM 258 kfg / cm2
Rotor #2 => 5.3, 5.8, 5.1 @ RPM 254 kfg / cm2
Rotor #1 =>5.6, 5.5, 5.5 @ RPM 258 kfg / cm2
Rotor #2 => 5.3, 5.8, 5.1 @ RPM 254 kfg / cm2
04-03-2011, 11:35 PM
#7
Another problem with remans is not the parts used, but how they are assembled. For years the rx7 remans have been of really questionable quality. I've taken apart tens of them myself. They always have a TON of sealant globbed all over the oil pan and also in other places where the factory never even called for sealant...such as on the front snout of the e-shaft where the gears and such get installed. This excess sealant can flake off of the pan and other areas and actually clog the oil pan pickup strainer. They also tend to be way off on their side seal clearances on the rx7 engines (I havent taken apart enough rx8 remans to judge them yet). Sometimes they do reuse a component that obviously should not have been. I've seen them reuse one iron with a streetport while using others with stock ports. I've seen them reuse rotors with previous significant apex seal slot damage. Or rotor housings with previous apex seal damage. I even once took apart a 93-95 rx7 engine (which would come stock with 9.0:1 compression rotors) that had blown apex seals on the front rotor (fairly unusual, usually the rear rotor blows first). As it turns out the reman plant had used a higher compression 9.7:1 rotor from an 89-91 non turbo in the front, and the correct 9.0:1 rotor in the rear.
I noticed my FC's oil pan have a TON of sealant all over. (all over the place?), the bolts are jammed with sealant when I took them out.
No idea who build the engine, the previous owner said the owner b4 him replaced the engine about 30K miles before he sold the car. probably bullshit and its just the original engine ? Who knows, I will find out when I break the engine apart this coming week.
if its a Mazda reman then I gotta say the build quality is pretty horrible.
Last edited by nycgps; 04-03-2011 at 11:38 PM.
04-04-2011, 02:12 AM
#8
kevin@rotaryresurrection
iTrader: (3)
Join Date: Feb 2005
Location: east of Knoxville, TN
Posts: 1,415
Likes: 0
Received 57 Likes
on
35 Posts
I just notice this thread, hmm.
I noticed my FC's oil pan have a TON of sealant all over. (all over the place?), the bolts are jammed with sealant when I took them out.
No idea who build the engine, the previous owner said the owner b4 him replaced the engine about 30K miles before he sold the car. probably bullshit and its just the original engine ? Who knows, I will find out when I break the engine apart this coming week.
if its a Mazda reman then I gotta say the build quality is pretty horrible.
I noticed my FC's oil pan have a TON of sealant all over. (all over the place?), the bolts are jammed with sealant when I took them out.
No idea who build the engine, the previous owner said the owner b4 him replaced the engine about 30K miles before he sold the car. probably bullshit and its just the original engine ? Who knows, I will find out when I break the engine apart this coming week.
if its a Mazda reman then I gotta say the build quality is pretty horrible.
The remans have a ton of sealant in places the factory never called for (such as tension bolt heads, eshaft snout), and in amounts 5 times what a single engine should have (enough to clog oil pan pickup strainers). The remans also often have a red anodized-looking paint/ink on the bolt heads of the front cover, front main hub bolt, flywheel nut and rear tension bolts. They usually have a blue tag on the front cover, and the front cover has silver paint that flakes off to reveal a dull gray aluminum finish underneath. It's usually pretty easy to spot them.
04-04-2011, 02:56 AM
#9
Also , for those who are out of warranty and don't want to spend big money on a replacement there is always stretching it out for as long as possible . which is why I made this thread :
https://www.rx8club.com/rx-8-discussion-3/think-you-need-new-engine-read-211913/
https://www.rx8club.com/rx-8-discussion-3/think-you-need-new-engine-read-211913/
04-04-2011, 03:24 AM
#10
I'd focus on getting a properly rebuilt engine from a reputable company (Not a mazda reman, for god's sake) and live with it... and a little premix 
I understand that it is frustrating but it's really all we can do when our engines bite the dust to ensure another long time of smiles.
Considering the cost of a bare engine and the difference in mpg that you get with a well built\kept one vs a crappy reman, i'd lean towards spending a bit more for a properly built engine and recover that gap during the life of the engine.
I understand that it is frustrating but it's really all we can do when our engines bite the dust to ensure another long time of smiles.
Considering the cost of a bare engine and the difference in mpg that you get with a well built\kept one vs a crappy reman, i'd lean towards spending a bit more for a properly built engine and recover that gap during the life of the engine.
04-04-2011, 02:59 PM
#11
Registered
Join Date: Nov 2009
Location: Kentucky
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
I haven't really been around long enough to be %100 sure, but I'd say most of these "won't start" or "low compression" threads are every bit as seasonal as first frost and spring bloom. These problems always seem to pop up with the onset of cold weather and continue through the spring warm up - both of which are ripe for cars misbehaving. I think everyone who owns one of these cars will inevitably run into one of these issues, and the first thing they'll do (myself included) is come here to post about it, and more often than not it winds up being something decidedly simple. With the relatively short life of coils/plugs, frequency at which the MAF and other components need to be checked and cleaned, etc -- I think a lot of people don't really see these symptoms until they manifest and are made worse by freezing temps or hot weather.
And like RotaryResurrection said, there are still a lot of early models out there with relatively low miles that are just now hitting that 50k-60k mark. I ALWAYS expect any car, regardless of who makes it or what kind of engine it carries around, to start having some issues around that mileage. Personally, I've never owned one that didn't.
And like RotaryResurrection said, there are still a lot of early models out there with relatively low miles that are just now hitting that 50k-60k mark. I ALWAYS expect any car, regardless of who makes it or what kind of engine it carries around, to start having some issues around that mileage. Personally, I've never owned one that didn't.
04-04-2011, 04:34 PM
#12
He's as bad as Can
Thread Starter
I have been around here since 2/2004 and this isn't a seasonal issue. Most of the owners that get a compression tests and have these symptoms have failed and require a new (rebuilt) engine.
During my time here I have noticed two periods where engine failure posts were frequent. The hot climate issue from 2005-2006 and the current low compression issue. Mazda seemed to have solved the first with some new flashes. The current one will not be Mazda's problem much longer when the bulk of the RX-8's on the road are no longer covered by the 8/100k which isn't that far away.
During my time here I have noticed two periods where engine failure posts were frequent. The hot climate issue from 2005-2006 and the current low compression issue. Mazda seemed to have solved the first with some new flashes. The current one will not be Mazda's problem much longer when the bulk of the RX-8's on the road are no longer covered by the 8/100k which isn't that far away.
04-04-2011, 05:45 PM
#13
Registered
Join Date: Nov 2009
Location: Kentucky
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
I have been around here since 2/2004 and this isn't a seasonal issue. Most of the owners that get a compression tests and have these symptoms have failed and require a new (rebuilt) engine.
During my time here I have noticed two periods where engine failure posts were frequent. The hot climate issue from 2005-2006 and the current low compression issue. Mazda seemed to have solved the first with some new flashes. The current one will not be Mazda's problem much longer when the bulk of the RX-8's on the road are no longer covered by the 8/100k which isn't that far away.
During my time here I have noticed two periods where engine failure posts were frequent. The hot climate issue from 2005-2006 and the current low compression issue. Mazda seemed to have solved the first with some new flashes. The current one will not be Mazda's problem much longer when the bulk of the RX-8's on the road are no longer covered by the 8/100k which isn't that far away.
04-07-2011, 10:07 PM
#14
Registered
Also another point I wanted to make. So much is made of mileage and reliability of these cars. IT wasn't that long ago (in terms of design and engineering), about 30-35 years ago, that cars were expected to last 75, maybe 100k miles and then they had served their purpose and were considered worn out.
These days if a car can't go 200k miles on all original drivetrain components, while getting nothing but fuel and oil changes every 5k miles, while getting 27mpg, while making at least 225hp, with a purchase price of under 20k new, then it is regarded by the public as an overpriced, unreliable, slow, inefficient piece of ****. I think some among us need to take a second look at our expectations. You can't always have your cake and eat it too.
These days if a car can't go 200k miles on all original drivetrain components, while getting nothing but fuel and oil changes every 5k miles, while getting 27mpg, while making at least 225hp, with a purchase price of under 20k new, then it is regarded by the public as an overpriced, unreliable, slow, inefficient piece of ****. I think some among us need to take a second look at our expectations. You can't always have your cake and eat it too.
I mean, after you put 300.000 plus miles on a little Corolla or Civic, you sort of get spoiled and think every vehicle should do the same.
But you are right. Some expectations are probably too high.
ON the other hand, the opposite is also true. With the way things have evolved over the past four decades, i don't think it's unreasonable to expect a car to run relatively trouble free for the first 100.000 miles.
Or so.....
04-09-2011, 05:39 PM
#15
He's as bad as Can
Thread Starter
Band Aid's for Low Compression??
I was thinking about possible aftermarket band aid's for low compression engines and these to came to mind.
A starter that spins 300-400 RPM? Would it be possible for someone to either make or modify a starter to spin even faster and would this help at all?
The second is the addition of premix / clean oil into the housings during start-up. The way I envisioned it would be a small bottle full of premix or oil connected to the nipples on the intake runners. A valve would be placed in-between the oil and the vacuum openings. It would only open when cranking the starter. The vacuum would draw in the oil during start-up and in theory add just a little more compression to help when starting.
Is any of the above feasible? I do see a growing market for this. Some vendor can create a Low Compression kit that includes the faster starter and supplemental oil kit.
A starter that spins 300-400 RPM? Would it be possible for someone to either make or modify a starter to spin even faster and would this help at all?
The second is the addition of premix / clean oil into the housings during start-up. The way I envisioned it would be a small bottle full of premix or oil connected to the nipples on the intake runners. A valve would be placed in-between the oil and the vacuum openings. It would only open when cranking the starter. The vacuum would draw in the oil during start-up and in theory add just a little more compression to help when starting.
Is any of the above feasible? I do see a growing market for this. Some vendor can create a Low Compression kit that includes the faster starter and supplemental oil kit.
04-11-2011, 04:02 PM
#16
Registered
Join Date: Nov 2009
Location: Kentucky
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
I was thinking about possible aftermarket band aid's for low compression engines and these to came to mind.
A starter that spins 300-400 RPM? Would it be possible for someone to either make or modify a starter to spin even faster and would this help at all?
The second is the addition of premix / clean oil into the housings during start-up. The way I envisioned it would be a small bottle full of premix or oil connected to the nipples on the intake runners. A valve would be placed in-between the oil and the vacuum openings. It would only open when cranking the starter. The vacuum would draw in the oil during start-up and in theory add just a little more compression to help when starting.
Is any of the above feasible? I do see a growing market for this. Some vendor can create a Low Compression kit that includes the faster starter and supplemental oil kit.
A starter that spins 300-400 RPM? Would it be possible for someone to either make or modify a starter to spin even faster and would this help at all?
The second is the addition of premix / clean oil into the housings during start-up. The way I envisioned it would be a small bottle full of premix or oil connected to the nipples on the intake runners. A valve would be placed in-between the oil and the vacuum openings. It would only open when cranking the starter. The vacuum would draw in the oil during start-up and in theory add just a little more compression to help when starting.
Is any of the above feasible? I do see a growing market for this. Some vendor can create a Low Compression kit that includes the faster starter and supplemental oil kit.
Last edited by Icky Mettle; 04-12-2011 at 12:43 PM.
04-12-2011, 10:33 AM
#17
They made me buy my RX8.
Join Date: Nov 2007
Location: Knoxville, TN
Posts: 270
Likes: 0
Received 0 Likes
on
0 Posts
Let me chime in as a recent new engine recipient.
My old engine was running fine. They said the compression ratio was 6.5 and the minimum Mazda would allow was 7.5. The norm is supposed to be about 10.0. I would say that one should probably not go by a compression test alone if one is being asked to shell out for the engine. I got mine under warranty, which is why I'm going to try and get rid of the car now. No doubt they put a piece of garbage under the hood. The car feels better now, like new, but it didn't feel "bad" on my old engine in the first place. I didn't have starting problems, low power, or any of the issues that creep up with bad engines.
So I would say, go with how the car feels. If it is running fine and starting fine, and you still have juice to pass people on the interstate or at stop lights, then save yourself the trouble. All cars lose compression and power as they age. This one loses it at a slightly faster rate.
My old engine was running fine. They said the compression ratio was 6.5 and the minimum Mazda would allow was 7.5. The norm is supposed to be about 10.0. I would say that one should probably not go by a compression test alone if one is being asked to shell out for the engine. I got mine under warranty, which is why I'm going to try and get rid of the car now. No doubt they put a piece of garbage under the hood. The car feels better now, like new, but it didn't feel "bad" on my old engine in the first place. I didn't have starting problems, low power, or any of the issues that creep up with bad engines.
So I would say, go with how the car feels. If it is running fine and starting fine, and you still have juice to pass people on the interstate or at stop lights, then save yourself the trouble. All cars lose compression and power as they age. This one loses it at a slightly faster rate.
04-12-2011, 12:15 PM
#18
Administrator
iTrader: (7)
great thread.
Expo: You and I talked about this before and I agree that it really is a shame to only get 40,000 miles out of a quality rebuild. For the money spent, it would be nice to get more especially considering your 1st motor went well over 100,000 miles so unless those rotor housings in your current build had 60,000 + miles...
Expo: You and I talked about this before and I agree that it really is a shame to only get 40,000 miles out of a quality rebuild. For the money spent, it would be nice to get more especially considering your 1st motor went well over 100,000 miles so unless those rotor housings in your current build had 60,000 + miles...
04-12-2011, 08:29 PM
#19
kevin@rotaryresurrection
iTrader: (3)
Join Date: Feb 2005
Location: east of Knoxville, TN
Posts: 1,415
Likes: 0
Received 57 Likes
on
35 Posts
You might be on to something. Seems like some people only have compression issues on startup. Our stock (Rev B) starter spins at what, 280 RPMs off of 9 volts? If so, then it's just about there. I wonder if going to 12 volts would crank up the speed of the stock starter? Or maybe it's already running at 12 volts, I don't know, but I thought it was originally built as a 9 volt. I also like the oiling idea, but would that also increase the potential for flooding/plug fouling due to hard starts caused by possible low compression? I don't know -- lots of people say their cars suck at starting but run fine afterwards, so I think there's some practical value in maybe testing something like this.
04-12-2011, 08:48 PM
#20
Registered
Join Date: Nov 2009
Location: Kentucky
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
06-06-2011, 01:31 PM
#21
Registered user
iTrader: (7)
Join Date: Feb 2011
Location: NC
Posts: 700
Likes: 0
Received 0 Likes
on
0 Posts
Is it just me or have threads on this issue increased over the last six months? I am beginning to have doubts about long term ownership of this car.
I am on my 2nd engine and it just failed a compression test, I am also having warm starting issues. I put about 40,000 miles on the 2nd engine pre-mixed and ran 5W-30 Royal Purple ( I don't wish to get into an oil debate) I at 153,000 miles I am on my own again. I was messaging an engine builder and he said 40,000-50,000 miles on a rebuilt wasn't that bad. That when re-using rotor housings one needs to take into account that its a wear item and whatever miles it had on it when it was taken apart should be added to whatever you put on it. Weather its uneven APEX seal wear do to no 3rd OMP jet or housing wear these engines just loose compression faster than piston cars.
This made sense to me, that the only way to expect 100,000 miles from a rebuilt is if it used NEW housings. That brings the total cost of a rebuilt to over $5,000. So the people installing engines that reuse housings are not going to reach 100K no matter how they take care of it? Dropping $4,000 every 50,000 miles is something I don't wish to do. Does anyone know if the rebuilt engines the dealerships use come with new housings?
I guess what I am asking here is for other opinions about rebuilt longevity and has anyone else also noticed a increase in compression related threads. Since the majority of RX-8 on the road are 2004 & 2005's engines failure threads could continue to grow and further tarnish the cars rep.
I am on my 2nd engine and it just failed a compression test, I am also having warm starting issues. I put about 40,000 miles on the 2nd engine pre-mixed and ran 5W-30 Royal Purple ( I don't wish to get into an oil debate) I at 153,000 miles I am on my own again. I was messaging an engine builder and he said 40,000-50,000 miles on a rebuilt wasn't that bad. That when re-using rotor housings one needs to take into account that its a wear item and whatever miles it had on it when it was taken apart should be added to whatever you put on it. Weather its uneven APEX seal wear do to no 3rd OMP jet or housing wear these engines just loose compression faster than piston cars.
This made sense to me, that the only way to expect 100,000 miles from a rebuilt is if it used NEW housings. That brings the total cost of a rebuilt to over $5,000. So the people installing engines that reuse housings are not going to reach 100K no matter how they take care of it? Dropping $4,000 every 50,000 miles is something I don't wish to do. Does anyone know if the rebuilt engines the dealerships use come with new housings?
I guess what I am asking here is for other opinions about rebuilt longevity and has anyone else also noticed a increase in compression related threads. Since the majority of RX-8 on the road are 2004 & 2005's engines failure threads could continue to grow and further tarnish the cars rep.
06-06-2011, 08:01 PM
#24
you don't want to say that.
cuz if u read thru the whole thread, it tells you the re-man engine of "that time" use a lot of used parts. It applies to almost ALL engine rebuilding service at that time. Not just this vendor. It's a way to keep the cost low (and be more competitive)
honestly, when you re-use rotor housing, 50K miles is actually pretty good.
the reason I said that (I'm not on anyone's side)
cuz if you have EVER opened an engine yourself and see the housings yourself, you will know that 90% of the time the rotor housing will have damage. It's might be "somewhat usable", not the best if longevity is your main concern. BUT again to make the price more affordable. lots (or most) people would go for the "reusing the rotor housing" option. by using this option, you should be able to get an "engine" back for less than 3K. (or even in the low 2K range)
Now the vendor, as far as I know, already stop offering the "low price" option. because this will make the rebuild quality 10 times better and their on-site builder is one of the best in the nation. bad thing about this is that ---- it WILL increase the overall cost, to almost 5K
Remember, you get what you PAID for.
This vendor and Kevin @ Rotary Ressurection both makes great rebuild.
cuz if u read thru the whole thread, it tells you the re-man engine of "that time" use a lot of used parts. It applies to almost ALL engine rebuilding service at that time. Not just this vendor. It's a way to keep the cost low (and be more competitive)
honestly, when you re-use rotor housing, 50K miles is actually pretty good.
the reason I said that (I'm not on anyone's side)
cuz if you have EVER opened an engine yourself and see the housings yourself, you will know that 90% of the time the rotor housing will have damage. It's might be "somewhat usable", not the best if longevity is your main concern. BUT again to make the price more affordable. lots (or most) people would go for the "reusing the rotor housing" option. by using this option, you should be able to get an "engine" back for less than 3K. (or even in the low 2K range)
Now the vendor, as far as I know, already stop offering the "low price" option. because this will make the rebuild quality 10 times better and their on-site builder is one of the best in the nation. bad thing about this is that ---- it WILL increase the overall cost, to almost 5K
Remember, you get what you PAID for.
This vendor and Kevin @ Rotary Ressurection both makes great rebuild.
Last edited by nycgps; 06-06-2011 at 08:23 PM.
