JinkoMK

For the past few weeks now I have been toying with the idea of going forced-fed but have been thinking quite a lot about which turbo mounting would be a better option. I guess it would depend on the purpose of the car but I'd like to hear some of your inputs on whether the points I'm about to make are accurate or not.

Top mount seems to be to go-to choice. Lots of cars have already done it and Ric Shaw here in Sydney has done quite a few builds already. His preferred choice of turbo charger is the Borg Warner (not sure what model) so my sights are on the EFR 7670 Internal Wastegated Twin-Scroll. Paired with a rebuild using GSL-SE rotor housings and having each exhaust runner for each turbine housing would make a great combination. My only concern with this setup is that the exhaust manifold would run so close to the OMP that I'd worry too much about it failing, before even taking into consideration that I have the SOHN OMP Adapter. One of Ric's recent build was done on an S2 which doesn't have an OMP in the way to be concerned about.

Running on only premix is not something I would like to do as Eric Meyer points out the issues with deleting the OMP. TL;DR: Excessive side seal wear. Relocating the OMP isn't out of the question as the SOHN OMP Adapter brings a huge benefit to the table. Without the need for crankcase oil, the OMP can be relocated to anywhere mounted low in the engine bay. But of course, you will have to make new OMP lines as well as extending the OMP electrical wiring.

Low mount is an attractive choice for me to consider as it doesn't have to deal with the issue of having the OMP in the way. Having the turbo so close to the manifold would also help with turbo spool-up. The biggest draw back though is of course, limited space. Some research suggests that the EFR 7670 is way too large to fit in such a tight space. I'm not too up to date with other turbo options (still new to turbos in general) but I know Brettus is running a Garret GT3582R Twin Scroll in his RHD car making upwards of 400whp.

Both mounting options are hindered by the fact that we have a steering column in the way but seeing Brettus overcome this with great results is fantastic to see. With Ric Shaw previously owning the turbo RX8 SP, he should be very insightful on the best low mount setup that we can come up with. This sways me more towards the low mount option as I also want to be able to track the car with sufficient cooling, so Ric should have tons of ideas and experience to back up his work.

Why don't I just ask Ric to begin with you may ask? I'm easily years away from even going F/I so I don't want to disrupt the busy man just yet. Plus I wanted this to pan out into a nice discussion, hopefully.

9krpmrx8

iTrader: (46)

Well I have been running the Greddy kit with an upgrade turbo (54trim) for a few years (30,000 miles) and now that it is dialed in and running an E40 mix it is really nice, spools quick, great drivability. It's decently fast (faster than my stock single twin scroll 280-290WHP 335i) but not a monster by any means and since fast is subjective, well you need to decide what you want the car to do. But remember, it's a 1.3L Renesis. I would advise against the hybrid setup as they just haven't shown to make any more HP or be any more reliable than a normal properly built Renesis.

Downsides:

Getting the turbo in and out can be a bitch with a low mount and you can't run a "large" turbo and no the 7670 won't fit with the available manifolds.

As for top mount, well I have a PTP top mount kit sitting around and I also plan to run the BW EFR 7670 on it. It should be a great setup once I modify the PTP kit to suit and internally gated turbo and install a proper intake on it.

Downsides:

Location and Heat in the engine bay and depending on what manifold you use, OMP issues. I would never delete the OMP on a street car.

The RHD issue may be a significant obstacle to overcome but I am sure it can be done.

JinkoMK

I still intend on having this car as a daily that can stand up to track duties. That will be my ultimate goal I guess. Big numbers isn't a huge priority as long as it can take the abuse. But of course, I'll still want to make as much as reasonably possible.

Ric Shaw here has built a few hybrid engines with full bridgeports that made 30% more power (I won't quote hard numbers as all dynos are different). I know the Renesis tends to run into over heating issues with bridgeports but one fellow in Melbourne keeps us updated and has been to at least 5 track days with no issues. He's no amateur either. Still N/A though. Running well still after 3 years though time will tell if it's as reliable as a standard MSP.

EDIT: I also feel that a hybrid engine with two exhaust ports would suit a twin scroll more efficiently, but I'll have to look more into that.

Definitely agree. How feasible do you think relocating the OMP is? Never really seen anyone do it. Have you thought about your plans once you move over to top mount? Too close for comfort with the SOHN adapter attached...

EDIT 2: Also maybe worth stating that the RX8 SP made 100% more power over stock cars after he had a tinker with it. Not bad I guess for a low mount that can handle Targa Rallies, but I have no data on spool-up, etc.

9krpmrx8

iTrader: (46)

30% more power than what? If you block the middle port then yes a twin scroll would work. But why not just swap in a REW at that point?

Relocating the OMP is not feasible. You can do a top mount and keep the OMP. It just depends on what kit you go with.

As for stated HP, etc. well so much depends on that, you really shouldn't get caught up on dyno numbers as they are unreliable. Plenty of shops like PAC, Turdblown, Esmeril, Himni, etc. like to claim big numbers and they may hit that a couple of times but all of those engines have died in short order. Plus track builds don't have to consider overall drivability, they just care about how it runs in a certain range. A range that most street cars spend little time at.

JinkoMK

The new engine made 30% more power from stock. 133kW compared to 103kW. Surely blocking the Siamese exhaust port would make the MSP horribly inefficient. And a standard or hybrid rebuild plus turbo upgrade is still far cheaper then a REW swap, though I'm not ruling that option out just yet.

I trust Ric Shaw and his work the same way many here trust Eric Meyer and his words, certainly far more than the other incompetent shops around here. But yes, inflating power figures isn't something new and I'm aware of it. You're right about type of car builds though.

9krpmrx8

iTrader: (46)

Oh, well 30% more than stock NA has been done without needing to do all that. My buddies Drummond built Renesis made 268HP (flywheel)with no porting or crazy stuff. It's all about the tune, ECU used, header used, etc. The Koni challenge cars were in the 240-245WHP range on average with no crazy porting, etc.

A hybrid rebuild and a proper turbo build should cost you close to what a decent REW swap would and would likely be far more reliable and make more HP. Don't get me wrong, I am all about the Renesis but doing a renny hybrid makes no sense to me and is a huge risk for little reward.

9krpmrx8

iTrader: (46)

To get where I am now, I have spent $15,000.00 easy on the turbo build and engine rebuild.

JinkoMK

Cheap as chips compared to us. :laugh: But IIRC you rebuilt the engine yourself which would have saved labour costs.

yomomspimp06

^I'm pretty sure he's on a pineapple build...

9krpmrx8

iTrader: (46)

My engine was built by Pineapple Racing in Oregon.

reddozen

iTrader: (1)

I'm bridge ported on the secondaries. It did nothing but level out the mid range a little. Power gains are negligible.

The only thing "exotic" I would do is similar to what Chip is doing with that semi pport set up, but only if I was chasing NA power, and only if I could get a 2 piece eshaft (I wasn't able to). I have 3 PPort GSL-SE housings that I bought for the build. That build probably would have ran close to 20k or more at the end of the day.

I'm with 9krpmrx8. Save your time and money and go with an REW swap if you're wanting "big power" etc. CXRacing has a complete swap kit for $2,500 minus the motor, ecu, and fuel... they sell just the mounting brackets too etc if you rather have something higher quality made yourself.

cxracing.com: 13B Engine Mount Turbo Intercooler Piping Intake Manifold Kit For RX8 Swap

lastphaseofthis

I'm going to kill your project plans right now and here...
i thought about using gslse housing as well, but if you look at the OMP oil jets squirt on the side seals in rx8 housings, but gslse have just the one in the middle.

i have a BNIB gslse middle for deleting the Siamese port
i plan to drill and weld rx8 NEW housings for peri exhaust... to keep oil on the outside side seals.
you can copy me if you like.
also will a 8374 fit bottom mount? lets see..

yomomspimp06

no....The 8374 is HUGE! There is no way it'll fit bottom mount

reddozen

iTrader: (1)

I was thinking the same thing. Heat is already an issue with the side seal springs. I suppose you could premix also...

I'm with you though. Just mill out Renesis housings and save the complication. Would be ideal if you could run S2 Renesis housings as well. I think the new Adaptronics ECUs can run the S2 electric OMP (maybe it was a different ECU though). Then you'll have 3 injectors so you won't wear out the center of the apex seals as fast either.

JinkoMK

You can't use the S1 OMP on S2 housings though. It may be possible to machine oil injection ports into the GSL-SE housings and use the OMP. I'll have to dig deeper into it. I'm weary about exhaust peripheral porting the MSP housings as I don't think any of the metal epoxies like Devcon can handle the EGT. Once again, I'll have to sleep on it.

yomomspimp06

^have you seen Chip's peri housing? I don't think it using any metal epoxies

JinkoMK

I have seen it and it looks like Devcon steel epoxy to me. Very happy to be proven otherwise.

reddozen

iTrader: (1)

I was saying to use the S2 housings and S2 OMP. Just need an ECU that can run the electric OMP.

9krpmrx8

iTrader: (46)

No ECU that I know of can run the S2 OMPS (two of them) and the rest of the system. Plus you would need to drill an tap holes for the oil pan to work, etc, etc.

Brettus

iTrader: (2)

Would love to see you work some majic and make it fit !

lastphaseofthis

you dont have to use epoxy for my method.. while i have your attention.. i'll let give you a secret i have tucked away..i have made intakes this way, not exhaust yet..
1. drill 1/4 pilot hole.
2. hole saw at 44mm thru the first water jacket seal area and just start into the aluminum on the inside of the water jacket combustion seal.
3. drill 38mm hole all the way thru. weld an aluminum pipe 44mm outside diam. 40mm inside diameter it will only go up to the point you stopped in the water jacket.
NOTE: you can't go back and drill deeper with the pilot whole gone.. so you have to get it right the first time :P
the deeper you drill the first 44mm hole the closer you get to the chrome and the aluminum pipe can't be welded to the inside water jackets aluminum. but the closer is it to the chrome the easier it is for the welder to reach...
4. weld the outside housing to the pipe, sealing it. weld inside thru the 38mm hole, the pipe to the housing.

(for exhaust)insert a steel pipe inside the alum one. 39.5mm outside diameter and weld to the steel/chrome inside housing... carefully. i haven't done the double pipe yet...
for semi pp i would just use epoxy. why make small exhaust go 55mm yum yum
this is a steel exhaust pipe that i welded to a housing i went to deep with my 44mm cut. i then sanded it flush, .. i could epoxy this and still use it..but it's not as good as my alum double welded.


going to delete a/c and move the engine over like 8 inches.. hey at least its' a plan...(that i know won't work)

slash128

Just take out the engine entirely. Then you can fit just about any turbo you want in there