Another High comp + Boost thread

[andrew22888]

If your going for 300 whp goal why not just go NA and build a far more reliable engine. And not have to worry about boost leaks and what not. The compressor ratio your going for is far to high for a boosted engine. You can try it but I bet it won't last very long.

[sonikaccord]

Ethanol is pretty close to race fuel, it has some interesting characteristics. So external compression is easier for the engine to handle rather than the engine doing the compression during that particular stroke. I'll call Bisi tomorrow and see what he thinks about the aggressiveness of the timing, detonation and etc.

KeeleDesign airflow numbers does sound like a more appropriate measure of forced induction

Andrew22888: What's your reason that you think the ratio is too high? Why wouldn't it last?

wed3k: You speak of flat top pistons, and you actually just sold some high comp pistons I think. Is there a big difference in turbo pistons and N/A pistons.

The question about head flow and porting/polishing for forced induction, does it ease flow of air similar to what it does with an N/A engine or are the results negligible?

[prNonVtec4u]

you know what, you seem pretty set on what you wanna do. go fot it and let us know how it works. good luck and look forward for results.

[sonikaccord]

I'm looking for open discussion, I haven't made a decision on what I want to do yet. I will pick up some engine design books and pick more people's brains before I buy anything related to this thread. I can keep this thread updated though, might be a cool little paper project lol

[wed3k]

Ethanol is pretty close to race fuel, it has some interesting characteristics. So external compression is easier for the engine to handle rather than the engine doing the compression during that particular stroke. I'll call Bisi tomorrow and see what he thinks about the aggressiveness of the timing, detonation and etc.

KeeleDesign airflow numbers does sound like a more appropriate measure of forced induction

Andrew22888: What's your reason that you think the ratio is too high? Why wouldn't it last?

wed3k: You speak of flat top pistons, and you actually just sold some high comp pistons I think. Is there a big difference in turbo pistons and N/A pistons.

The question about head flow and porting/polishing for forced induction, does it ease flow of air similar to what it does with an N/A engine or are the results negligible?

yea about 3 points of compression lol.

like i said, flat tops are best for quench as well but hondas run well with 12:1's so a dome is needed.

porting/polishing eliminates a lot of turbulence in the ports. id still highly focus on the exhaust side of the f22a ports. the intake are already cast pretty well, just smooth out the casting and youll be good. ive came across stainless oversized valves that still fit on the stock seat. valve job and bowl work is crucial.

i do a lot of work on heads with minor port work on the exhaust, around the guide, performance valve job and people are always happy.

with forced air, anything on the intake side isn't necessary but it helps. more volume improves throttle response.

[KeeleDesign]

If your going for 300 whp goal why not just go NA and build a far more reliable engine. And not have to worry about boost leaks and what not. The compressor ratio your going for is far to high for a boosted engine. You can try it but I bet it won't last very long.

Incorrect. Boost puts less stress on a motor than a n/a that's has to rev higher.

300whp could easily be obtained on a motor with a big 16g, a small intercooler,mls head gasket, forged rods and pistons. 640cc injectors, 190lph fuel pump, and a decent tune.

High compression and supercharged and turbocharged all on the same engine is nothing new. Companies have experimented with this for years.
Their are tons of books on this topic.
In the end knock will be your enemy.
You may add 2 points of compression above 10:1 in doing so you may have to retard your timing.
A decent tune yields around 9-13hp per point of timing added in a specific rpm it has been added too.
1 point of compression yields around 10 hp per all rpms at all times.

Now to add 12:1 compression you have to retard your timing up to 5-7 degrees across the board after the onset of boost. This is a very conservative assessment too.
So you basically are sacrificing a potential 91hp with the onset of boost, so you can have an extra 20hp from beginning to the end of your rpm range.
water/meth injection will only combat so much. And the cost to run this setup would be ridiculous when lowering your compression would yield higher hp #'s on lower grade fuel without the fear of one thing not working, destroying your engine.

I've been where you are. I wanted it to work so bad, but you don't need to build this around a specific set of pistons you already have. It's not logical or affordable. Sell those pistons and grab a nice set of turbo pistons of 9:5:1. And yes the design charectoristics of na pistons vs turbo pistons are very different, not just in how they are shaped and made, but the positioning of the ringlands for a higher boost situation.

[sonikaccord]

This may be off topic but I still started this thread.

I'm seeing these technologies that use a turbocharged engine to modify an engines characteristics. Essentially the turbo is telling the engine how it should breathe.

Could a VGT/VNT style turbo be used to maintain optimal efficiency for the turbo by changing the A/R ratio to match the intended power level WHILE extending the power band by increasing the boost in proportion to the torque fall off at the end of the powerband to try to keep the torque constant?

Let's assume we have the control electronics to pull this off for now. This is completely theoretical.

[jdm92_accorn]

if it were me i'd stay in the 10:1 range and no higher than 10.5:1.
this is a thought.....

F22Ax head budget ported and milled .005"
bisimoto 1.2 turbo cam
valvesprings with oem retainers
F23Ax block bored 1mm over
RaceEng F23 rods
K24A2 JE 10:1 pistons (10.5:1 in the f23 with .005" off the head)
ARP head studs
precision 5858 turbo
BRM H23 ram horn turbo manifold
3" exhaust
1000cc injectors
walbro 255
hondata s300
hondata pwm boost contol
M2B4/T2W4 with accord 4.062 final drive
should be 400-425whp on 16-17psi and run mid to high 11's on slicks with with a good suspension in a 2700lbs cb7.

[sonikaccord]

That sounds like a good setup! Not too much power, but enough to get around a bit .

I'm all about drive ability, I'd take smoothness and predictability over max power. I guess I should start a new thread about my last post...