I agree. I would like more usable power down low myself. I am not sure if you saw my post on the power of the 8 but, I know even with it rated 232, many think that is still too high. The zr1 vette was recently dynoed at 505 to the wheels and is SAE certified at 638. Simple math says that is right at about 21% drivetrain loss. If you apply this to the 8, although 21% is rather high but yet certified in the case of the zr1, the 8 is now either right on with the hp and underrated in tq or, they fibbed badly with the zr1. In the case of my car, I had 133.7 wtq and if you divide by the .79 (21% loss) you get 169.2, meaning the tq is underrated. If you do the same math with the hp, my car, again, was 181.5 stock so that would be 229.7 which is slightly under the 232 now rated here in the US. I personally believe the the tq is underrated and that is why the car still runs mid 14s even after they downgraded it. My opinion.

 

/\ engine dynos put the renesis at around 215-220 flywheel HP

 

So all in all like I said I did understand heat being a issue. But everyone does agree with me 14 psi is 14 psi.... I can do a data log and show ya guys I feel boost right at about 3750 and have full boost by 5k and hitting 6k my power band kicking it is awesome as well. Second gear usually yields a good push into the seat at say 4k and at 6k you get a slight jerk do to the loss of traction and regain and get pushed into the seat even harder. But anyways I don't know what size turbo I have I just know I have the mazsport type 3 lol and yes I know I don't even know what size mine is...but do I really care....nope. All I know is it spools about where I like it to and it carries good power to 9k...that's all I care about. But I guess the other big thing that I never was putting into thought was ignition timing... mines not aggressive like at all....I'm sure I could put down a whole lot more power if I had the right timing..but my safety would go way down.

 

Oh and as far as his tq being down at 3k I'd have to say that has to do with his timing...I got great power down low...better then stock. Heck my gearing now is so high when I go threw town at like 50 I'm still in 5th gear running at like 1300 rpm and it's smooth maintains speed and can accelerate without a problem.

 

14psi is 14psi, right...
But how much air does your turbo moves at 14psi, how much does Chris'? psi doesn't mean flow which is what matters

 

OMG.
Guys. Stop. Seriously.

Why are you trying to undo all the clarification on how this works, all in one thread? (Not you, G)

Ugh.

 

Lol it's making sense to me.

 

nope : aux ports . Why would he run timing any different from stock when he has zero boost at that point ?
As for your low down power - I've seen a Mazsport dyno and it was all up top- much like the Esmeril .

Nope - not when you put it like that . Try reading the last few pages again.

 

I am a good padawan, am i?

 

Pressure means nothing, it's airflow. This has been beaten to death elsewhere.

Let's compare compressor maps (assuming we can all read them)

Here is a Garrett GT35R turbo:



And here is a Garrett GT2871R turbo:



Lets look at a pressure ratio of 2.5bar...at that PR the GT28 can only muster around 43lbs of air a minuet. But at the SAME pressure ratio (aka pressure aka boost) the GT35R does a whopping 61 lbs/min of air, a big jump of nearly 20 lbs/min of airflow (which is close to what a stock naturally apsirated Renesis flows at redline!)

Hopefully now you can see the difference in PSI/Pressure. It's airflow, not pressure, that matters.

 

Does not work like that either chicken ....

 

If only there were zillions of books that could be bought to help explain this whole thing....

 

Why do research when there are a zillion intawebz forum threads to destroy?

 

Yes they do

 

Look we know 14psi with one turbo isn't the same flow as the turbos. It's just that retard that doesn't

The main deal with relating flowrate vs pressure is in how MUCH flow the turbo can maintain at certain pressures. Your small turbo will start to "run out of steam" at higher revs, while the larger turbo will still be able to maintain pressure.

Let's say that you have two turbos... one is capable of 600cfm @ 15psi, and one is capable of 300cfm @ 15psi. Now let's take a theoretical engine that chugs 50cfm of air (naturally aspirated) per 1000rpm.

At 2000rpm, the engine only uses 100cfm at atmospheric pressure. The small turbo can maintain 300cfm at 15psi, and the larger turbo can maintain 600cfm at 15psi... both only need to supply 200cfm total (engine wants 100cfm at atmospheric, then add another 100cfm to boost 1 bar/atm) to maintain a +1 bar positive manifold pressure (or 14.7psi), so both will produce the same amount of power at that engine speed and boost level.

At 3000rpm, the engine wants 150cfm at atmospheric, so you need 300cfm to maintain 15psi of boost. No problem for either turbo here either- they can both maintain 300cfm at 15psi.

Once you step the engine up to 4000rpm, it wants 200cfm. To maintain 15psi of boost, you'll have to flow 400cfm into the intake manifold- and here is where the small turbo starts to choke. It's now operating outside its efficiency range, and it can't supply 400cfm of air to the engine. It can try- but it'll be spinning so fast that it does more work heating the air charge than compressing it. You start running into supersonic blade tip speeds, cavitation, etc- then a turbo that starts caramelizing its oil supply and starts to die. The larger turbo has no problem- it's still well within its efficiency range. It can flow 400cfm with no problems.

Since it can go to 600cfm at 15psi, it can maintain boost on that engine all the way to 6000rpm. It's supplying the 300cfm to satisfy the engine's atmospheric pressure needs, then another 300cfm to increase intake manifold pressure to 15psi (well 14.7 really).

Understand how it works? I could draw you some diagrams, but I don't really feel like it right now...

oh and regarding the compressor maps - read this http://www.turbobygarrett.com/turbob...o_tech103.html

 

Actually, in a simplified way, it does.

BTW - You can't use CFM, either. It doesn't account for temperature.
Since temperature is at the heart of mass, you must use mass (pounds or grams), which will also account for flow (CFM).

 

True - The intake system will only handle so much flow. Say the flow is maxed out at 12 psi and you are running 15-16 psi. That will create a lot of heat. The boost pressure may indicate 15 or 16 psi but there are no more air molecules in the intake charge than a cooler 12 psi intake charge. After a certain point, increased boost gives decreased intake charge density plus more heat and detonation plus increased ignition retard. Increasing the boost begins to give rapidly diminishing returns until a point of negative return is reached.

 

For the point of this simple comparison, yes, it is...

 

This line of thought makes Jesus cry.

 

Maybe we need another butt in hear to clear up the issue.

 

Complete rubbish and absolutely wrong.

Please people - enough of this. Its getting ridiculous.

There are a whole slew of threads on this board alone that correctly explain the whole flow/boost relationship and the relationship of density mass and temperature.

Stop with the attempted "lay" regurgitation.

 

what if I did a Dr Evil on you and found a turbo that would flow one MILLION pounds/min at 2.5bar .
Sure the turbo would flow it but would the Renesis - I think not .

My point is just because your GT35R CAN flow 61lbs/min at 2.5bar does not mean that it WILL flow it if hooked up to a renesis and run at that pressure .

It will flow what the Renesis will let it and if that happens to be in the sweet spot of the 35R and outside the sweet spot for the 28 then there will be a difference in flow at the same pressure due to higher temp. air from the smaller turbo .
However at some pressures when both turbos are inside their sweetspots the flow will be near as damnit the same .

 

Apparently their brains are being cryogenically maintained at 0 deg Kelvin for maximum mass density

will you guys please warm up to what the Mass-ter has repeatedly told you

 

I would worry about the turbo lag.

 

AAAAAAAAAHHHHHHHHHHHHHHH!

You don't get it either!

The pressure ratio is the result of the flow, not the other way around!
OMG. I am really worn out. Maybe its me. I dunno. It is so simple to me.
Its like filling a glass - you don't know how much you poured - you just see that it is full.

Whatever. I can't keep going with this.
Good luck to all of you.