[charlie66]

Hi everyone , I finally got a chance to dyno my turbo charged 194.5 ci 4 cylinder this passed week. I tried 30 psi 34 psi 38 psi and 40psi. The results were: @ 30-549 hp 34-606 hp 38-616 hp and 40-612 hp. These numbers are at the back tire not the flywheel..

The car is a 1964 Tempest lemans . It has a turbo 400 with a 9" rear 3:50 ratio with mickey pro drag radials.

As you can see the jump from 34 psi to 40 was only 6 hp. So I went out the other day and checked the exhaust back pressure and this is what I found:

@ 30 back pressure is 38.Thats 1.26 ratio. 8+ more psi .Air temp went from 50-148=98 rise

35 psi BP was 46 11+ more. Ratio 1.31 Air temp 57-162 105 rise. 7 more then 30 psi run.

39.4 psi BP 56 18+ more . 1.43 ratio. Air temp 51-170= 119 rise.

The turbo is a 76mm with a .68 A/R . I have a .81 A/R that I just installed but still have to check the BP.

If this doesn't fix the problem I will check the pressure differential before and after the intercooler just to make sure the turbo is in range with what it should be.

The fuel being used is e85.

__________________

[johnta1]

Nice!

Good power from a 4 cylinder.

What size is the exhaust system?



PS: 3.15 HP/CID awesome power.
(from wheel HP)

[Tom Vaught]

Originally Posted by johnta1

Nice! 3.15 HP/CID awesome power.
(from wheel HP)

Engine HP assuming a 15% loss thru the drivetrain/tires is:

612 x 1.15 = 703 HP divided by 200 cid = 3.51 HP per cubic inch on a engine dyno.

Basically with boost and a V8 engine and Charlie's set-up he would have a 1400+ HP street car with 2 turbos and a 400 cid engine.

Tom V.

[charlie66]

Thank you.
Its 2 1/2 to the turbo and 3 1/2 out the back..

[charlie66]

What is the general rule of thumb with the percentage drop in hp with a turbo 400 and a 9" rear? Im trying to figure a ball park hp number its making at the crank. 22% says 770 hp..

[twov8sandat4]

Originally Posted by charlie66

What is the general rule of thumb with the percentage drop in hp with a turbo 400 and a 9" rear? Im trying to figure a ball park hp number its making at the crank. 22% says 770 hp..

What chassis dyno was yours on?

For fun internet comparison, my 1994 Eagle Talon AWD with a 149cid engine, 5 speed, and 70mm Garrett GT4294 turbo at 45 psi made 613.8 hp to all four wheels. This was on a Dynojet awd dyno.

I love your car!

[BruceWilkie]

Originally Posted by twov8sandat4

What chassis dyno was yours on?

For fun internet comparison, my 1994 Eagle Talon AWD with a 149cid engine, 5 speed, and 70mm Garrett GT4294 turbo at 45 psi made 613.8 hp to all four wheels. This was on a Dynojet awd dyno.

I love your car!

Good numbers, good VE is tough to beat, but consider how much wheel power would drop if you had an automatic trans to push through.

Charlie's numbers are very respectable for 6500 rpm he limits to and t400 trans to put power through.
There is more in it once he finds out what's choking it.

[charlie66]

Originally Posted by BruceWilkie

Good numbers, good VE is tough to beat, but consider how much wheel power would drop if you had an automatic trans to push through.

Charlie's numbers are very respectable for 6500 rpm he limits to and t400 trans to put power through.
There is more in it once he finds out what's choking it.

I checked the pressure at the turbo and its the exact same as in the plenum.. So its not that.

Changed the A/R from a .67 to a .81 and the numbers went from @ 30 psi BC 38 to now 32. 35 psi now went from 44 to 40 and 40 psi went from 58 to 50. So I think it was worth changing to... What do you think?

[twov8sandat4]

Originally Posted by BruceWilkie

Good numbers, good VE is tough to beat, but consider how much wheel power would drop if you had an automatic trans to push through.

Charlie's numbers are very respectable for 6500 rpm he limits to and t400 trans to put power through.
There is more in it once he finds out what's choking it.

Yes. General rule of thumb we use in DSMs for manual, awd is ~25% loss, probably is much higher with automatic. I posted my results because they were within 2 whp of his with roughly the same losses as his t400 and 9". Two totally different setups making almost the same power His is more impressive though

[JSPONT]

Charlie, you wanted me to give you the leave? I think I need at least the leave!! Maybe 2 cars and the leave.

[charlie66]

Originally Posted by twov8sandat4

What chassis dyno was yours on?

For fun internet comparison, my 1994 Eagle Talon AWD with a 149cid engine, 5 speed, and 70mm Garrett GT4294 turbo at 45 psi made 613.8 hp to all four wheels. This was on a Dynojet awd dyno.

I love your car!

Thank you

This was a dynojet too.

I bet your car fly's. FWD must just hook and go. Sounds cool!

[charlie66]

I just read your P.S. I never thought of that.

Thank you...

[PAUL K]

Good job and interesting information ! Thanks for sharing.

[OCMDGTO]

That's incredible! You are embarrassing us V8 guys!

[charlie66]

Originally Posted by OCMDGTO

That's incredible! You are embarrassing us V8 guys!

Lol, Thank you.

All you have to do is turn the boost up to fix that . Hahaha..

Being this motor is half of a 389 , I think it would be safe to say a 389 would have made close to 1200 hp at the wheels at the same boost level.....

[charlie66]

Originally Posted by PAUL K

Good job and interesting information ! Thanks for sharing.

Thank you.

You're welcome. I'm trying real hard to figure out all the bugs I have had. I've come along way in doing so, so far , but still have a few still remaining, like the back pressure one.

[ponjohn]

What does this car run in the 1/4?

[charlie66]

Originally Posted by ponjohn

What does this car run in the 1/4?

I don't know yet. I will need a roll bar first I think or I would get kicked off. I think if i could get a 1.3 60ft it would go 9's. It feels real good I can say that...

[Tom Vaught]

Charlie, Steve Morris who does a lot of BB Chevy Boosted Engines was running a similar test on a Detroit Area 509 CID "street car" when I was at his shop one time.

The boost pressure went up in the intake manifold but the engine did not make the expected extra power.

Steve eventually ordered a different intercooler for his dyno and the engine went back on the dyno.

Now the 509 engine made over 2000 hp vs being stuck around 1750 HP.

This was due to an inlet restriction before the heads. In his case it was the dyno intercooler. In your case it might be the throttle body, intake runners, or actual intake ports themselves. So what you observed is very possible.

Tom V.

[charlie66]

Originally Posted by Tom Vaught

Charlie, Steve Morris who does a lot of BB Chevy Boosted Engines was running a similar test on a Detroit Area 509 CID "street car" when I was at his shop one time.

The boost pressure went up in the intake manifold but the engine did not make the expected extra power.

Steve eventually ordered a different intercooler for his dyno and the engine went back on the dyno.

Now the 509 engine made over 2000 hp vs being stuck around 1750 HP.

This was due to an inlet restriction before the heads. In his case it was the dyno intercooler. In your case it might be the throttle body, intake runners, or actual intake ports themselves. So what you observed is very possible.

Tom V.

Hi Tom,

So I guess now its all about finding out what's causing this choke point im seeing. What do you think about the possibility of it being from the exhaust housing ? The throttle body I have on it now is a 75 mm. What size would you think it would need to be in my case @ 40 psi?

I was thinking that it might be the intercooler. That will be my next place the check. If the turbo is making 50 psi and its coming out of the cooler at 40 psi im sure the turbo at this point will be very unhappy right?

P.S. Tom , I want to thank You for all of the help you have given since day one. You have been a wealth of great information for me through this whole build between you sizing the turbo and tolerating all my phone calls to you filled with questions....