Compound boost.

[justatroll]

@Jaden
Found an online calculator that gives different answers than mine above (and closer to yours): https://www.maperformance.com/pages/...ize-calculator

Stock engine: 200 hp, AFR 12, BSFC .40, charge temp 105F, VE = .95, RPM 6500, disp 122 in^3
0 boost required, 16 lbs/min air flow

Engine: 500 hp, AFR 12, BSFC .40, charge temp 105F, VE = .95, RPM 6500, disp 122 in^3
23.7 PSI boost required, 40 lbs/min air flow

So that is closer to your numbers.
And I found a third online calculator that was off by a factor of 100X (and pointed it out to the provider), so you cant trust online calcs always.

[EAGLE5]

OMG! Justatroll joined the thread. This is gonna get good!

In other news, there was a twincharged Civic that did well in some FWD time attack several years ago. Seriously impressive engineering. The engine still blew. Enmo.ca

[DustinS]

Twin Charged Lotus

Good Read on Superstreet about the Twin Charged Lotus. No bypass, just turbo feeding into supercharger.

VF MP62 supercharger; Precision 6262 turbo w/1.06 turbine housing

580hp

0-60mph in 2.2 seconds

[ajc209]

Originally Posted by weederr33

I was thinking something like the cosworth kit paired with the avo turbo kit since it's mounted low and out of the way.

AVO is already a small turbo with very little lag though..... might as well just spin the cossy SC to 400hp.

[wparsons]

Originally Posted by Jaden

Pressure is NOT meaningless.

Pressure is meaningless because it's airflow that makes power, not pressure. Pressure is a byproduct of how much airflow you're pushing in compared to what the engine can ingest.

No one is claiming pressure doesn't matter in the end, just that talking in terms of pressure when you're already looking at airflow is pointless.

[wparsons]

Originally Posted by Jaden

That's a reasonable opinion to have. I'm just not going to be so quick to agree with it, and it's my money... So, I'm going to feel free to test that out for myself..

Also, when you have someone with a 2.0 liter making 600hp running 8's in a 3000lb car, it kind of disagrees with you as far as the efficiency in the lower rpm ranges. Sure if he were to pull off the second turbo, he might make 800hp, but then he'd be running high 9's instead of high 8's. Remember, this is ALL based on real world examples, not theory. HE ACTUALLY ran 8's at 600hp in a rwd converted DSM. People running the same primary turbo he was running by itself making 800hp even in AWD never got out of the high 9's low 10's.

I also know that also doesn't matter that much to you since you are a track guy.

Jaden

So many variables at play, yet assuming it was all because of the hp/tq curve. Do you actually have the dyno plots of the similar cars to compare to his? How about full slips to see where exactly he's making up his time?

It could be chassis setup, grip, etc, etc, etc making up a lot (or all) of the difference too.

But hey, lets assume 100% of the difference is on one assumption.

[DustinS]

Okay. So doing more research on this. Kind of making plans. I have a friend doing a twin turbo V6 swap in an S2000 with custom A/C lines. As long as I can talk him into doing the A/C hard line on my car. I think I can get a V-Mount to work.

Using a greddy kit Evasive did a V-Mount for their pikes peak car








Running SBD kit (effectively the same kit)



My Current Turbo kit^^

So plans are the cut the straight section out of the manifold, effectively dropping the turbo down quite a bit. Using a Tial V-Band Exhaust housing to make mounting a little easier (and what is not to love about a Tial Housing). Also mounting an external Wastegate. This should allow me more room to get the intercooler in place and air routed correctly/better. Only hurdle will be how tall the Cosworth kit sits.

Was already planning on building the engine over winter. Element Tuning Built w/ head package. So this could get interesting. If it doesn't work, sell the supercharger/turbo and mount a GTX3076 on the manifold and I have a sick V-Mount set-up with A/C.

Running a V-Mount should take care of Heat Exchanger/intercooler cooling issue. The Cosworth A2W intercoolers have been proven to be super effective, so intake temps shouldn't be an issue at that point. Now I need to find a place to tune the car, I have a feeling I will be spending 15hrs+ driving to a tuner...

[Spartarus]

Originally Posted by justatroll

@Jaden
Found an online calculator that gives different answers than mine above (and closer to yours): https://www.maperformance.com/pages/...ize-calculator

Stock engine: 200 hp, AFR 12, BSFC .40, charge temp 105F, VE = .95, RPM 6500, disp 122 in^3
0 boost required, 16 lbs/min air flow

Engine: 500 hp, AFR 12, BSFC .40, charge temp 105F, VE = .95, RPM 6500, disp 122 in^3
23.7 PSI boost required, 40 lbs/min air flow

So that is closer to your numbers.
And I found a third online calculator that was off by a factor of 100X (and pointed it out to the provider), so you cant trust online calcs always.

The calculators are only as good as the inputs.

BSFC is not a fixed value, especially when turbocharging. Neither, curiously, is VE.

[scmil95eg]

Originally Posted by Spartarus

The calculators are only as good as the inputs.

BSFC is not a fixed value, especially when turbocharging. Neither, curiously, is VE.

Beat me to it.

BSFC for F/I on pump gas will be somewhere between .62 and .65 lb/hr per hp

VE for boost should be easy if you understand that we live in a 14.7 psi atmosphere. 14.7 + (boost)/14.7

Recalculate.

[Jaden]

Originally Posted by justatroll

@Jaden

I am having some difficulty with some of your numbers.

Disclaimer - Some of these numbers are guesses (e.g. BSFC = .4), if you have better values, please provide them and I can recalculate

First lets verify that we have starting numbers right.

In stock form, the FA20 does:
Stock engine: 200 hp, AFR 12, BSFC .40, charge temp 105F, VE = .95, RPM 6500, disp 122 in^3
0 PSI boost required @ 16 lbs/min air flow

But you mention:


Which doesnt make much sense.
for one example: to get 80-90 lbs of air flow in this engine (@3300 RPM) you would need ~130 PSI boost (or 62PSI @ 6500RPM)

My calcs show:
Stock engine: 500 hp, AFR 12, BSFC .40, charge temp 130F, VE = .95, RPM 3300, disp 122 in^3
64.2 PSI boost required @ 40 lbs/min air flow

So when you say "That should give you 20 psi at 3300 rpm with the air flow to be making 450-500 hp" I think you are off on your required boost by a factor of ~3X.

Even if we assume you can get the intake charge temp down to a non-boosted value (105F) you get:
Stock engine: 500 hp, AFR 12, BSFC .40, charge temp 105F, VE = .95, RPM 3300, disp 122 in^3
60.89 PSI boost required @ 40 lbs/min air flow

So by running at 105 F intake charge temp, you only reduce the required boost by ~3.5 PSI

Just trying to understand where you are coming from.
This is a fascinating topic for me.

On a related topic: I SWEAR that Toyota had a production MR2 with compound boost, but I can find no mention of it.
Perhaps it was only a prototype I read about in the 80-90s??
Anyway one of the concepts I found intriguing was that the SC output could be routed to the turbo while the car was idling to keep the turbo spun up.
I dont recall how they accomplished this but it was an interesting concept.

I didn't say that you would be making 450-500 hp at 3300rpm.

What I said was, that the FI system would be providing 13 psi at 3300 and ENOUGH airflow from the FI system to make 450-500hp.

The engine at 3300 likely wouldn't be able to make 450-500hp at 3300 rpm.

The engine has to be able to ingest 45-50 lbs a minute at 13 psi and 3300 rpm to make that much power. Which also proves my point about maximum engine airflow versus maximum compressor airflow.

What I said was that being able to provide 45-50 lbs a minute AND 13 psi AT 3300 will net you MUCH higher torque at 3300 than a single turbo capable of providing 80lbs a minute at 7500 rpm will on a 2.0l motor at 3300 rpm.

That's because that big of a turbo isn't going to be able to provide 13-17 psi of boost at 3300 rpm like a compound system will be able to.

Jaden

[Spartarus]

Originally Posted by scmil95eg

Beat me to it.

BSFC for F/I on pump gas will be somewhere between .62 and .65 lb/hr per hp

VE for boost should be easy if you understand that we live in a 14.7 psi atmosphere. 14.7 + (boost)/14.7

Recalculate.

Remember, VE is volume. The increased charge density (Boost) doesn't figure into the volume calculation, It figures in as increased mass flow (elsewhere in the equation), but the "VE" figure in the equation relates specifically to the volume of air ingested, independent of the density of that air.

BSFC is affected by AFR, Timing, engine load, Overlap, Octane, Ethanol content, overall compression ratio, overall expansion ratio, the ratio between those two, compressor efficiency, Intake/Exhaust pressure ratio, and more. It can get all the way down in the .4X's with proper tuning and proper setup. It changes throughout the powerband.

Even with correct multivariate regression, those equations are a guess. An approximation.

[CSG Mike]

Originally Posted by DustinS

Okay. So doing more research on this. Kind of making plans. I have a friend doing a twin turbo V6 swap in an S2000 with custom A/C lines. As long as I can talk him into doing the A/C hard line on my car. I think I can get a V-Mount to work.

Using a greddy kit Evasive did a V-Mount for their pikes peak car








Running SBD kit (effectively the same kit)



My Current Turbo kit^^

So plans are the cut the straight section out of the manifold, effectively dropping the turbo down quite a bit. Using a Tial V-Band Exhaust housing to make mounting a little easier (and what is not to love about a Tial Housing). Also mounting an external Wastegate. This should allow me more room to get the intercooler in place and air routed correctly/better. Only hurdle will be how tall the Cosworth kit sits.

Was already planning on building the engine over winter. Element Tuning Built w/ head package. So this could get interesting. If it doesn't work, sell the supercharger/turbo and mount a GTX3076 on the manifold and I have a sick V-Mount set-up with A/C.

Running a V-Mount should take care of Heat Exchanger/intercooler cooling issue. The Cosworth A2W intercoolers have been proven to be super effective, so intake temps shouldn't be an issue at that point. Now I need to find a place to tune the car, I have a feeling I will be spending 15hrs+ driving to a tuner...

I'd love to see the end product.

[killboy]

Originally Posted by CSG Mike

I'd love to see the end product.

[ame="https://www.youtube.com/watch?v=OKnyCsMqkBo"]Mackin FR-S at Pikes Peak 2015 (Scion Racing) - YouTube[/ame]

http://www.superstreetonline.com/vid...5-25213/25213/

1:25 is pretty telling.

In 2016 they switched to a 2JZ

https://www.scion.com/scionracing/97...kes-peak-2016/

[CSG Mike]

Originally Posted by killboy

http://www.superstreetonline.com/vid...5-25213/25213/

1:25 is pretty telling.

In 2016 they switched to a 2JZ

https://www.scion.com/scionracing/97...kes-peak-2016/

I meant the proposed compound setup. I'm very familiar with the Mackin car.