Preliminary numbers are in on my C5Z.

SAE


STD


We made 11 pulls without a hitch, Pulls were made at full temp(190*) with no more then a few minutes cool down time in between so its a more real world scenario. First off, we know that we under-cammed the car, I had bought the Arun Stg 2 cam (226/238) when I was originally going to do a 346/D1sc combo, then I changed build plans and since I already had the cam, I decided to use it...

*We think the cam is probably just too small to feed the motor AND carry it out to higher rpms... So we will likely get with Arun about something custom for it IF I cant get the numbers I want. But we are going to try to do it with the small cam first.

*Next, the logs show that the boost peaks at around 5800 and holds, it does not increase any more as it should as rpms climb.... The log was showing around 15 psi of boost at 5800 and just holding there. SO... we are either getting some belt slip past 5800 or something else going on, we suspect the blower inlet pipe or the intercooler is restricting it.


In a few weeks I will put the car on a local well known dyno to test a few things, mainly the inlet pipe vs. a velocity stack, get some synthetic oil in it and also a few more miles on it. Really want to do some more data logging to see if we can detect belt slip or what. If the velocity stack solves the KPA flat line mystery, and gains power up top, then we may pulley it down some.

*The 4.25" pulley is too big, we will likely be changing pulleys to a 4.00" to bring the blower in sooner and make more peak boost. It will still peak power early until we swap cams but atleast it will make more power before it peaks. I want to make sure the belt is not slipping up top though with the 4.25" pulley before we pulley it down.

Shooting for an honest 900rwhp with no tricks.

One thing I noticed is comparing the power band from 5200 and down, its as strong as most other 900-950 rwhp 408/427 SC'd builds so clearly, its something in the last 1500 rpms thats causing it to go flat. The tune was conservative with 16* timing and 10.5 afr.


For now, its time to cruise and hit some shows/races and enjoy the car as its been down for 8 months.

 

Im impressed.

That torque curve is crazy.

 

Thanks...

Yes, everything from 5000 rpms down is phenominal...... From 5000 rpms up, I have to find the plug... There is an obvious air flow issue after 5500..

Gotta love 511hp/669 tq at 4000 rpms though....

 

Looking Good!

I assume you are having good luck with the H2 motor?

 

Yes Bryan,

The H2 engine has been flawless to this point. So far we only have about 100 miles, some highway pulls and Dyno time on it but.... So far, so good.

Bret has been tuning it and the mild cam has made the car drive really nice off boost.. Very torquey off boost as well.

We'll see how the motor holds up over time but, I am very confident in it. Beau did an excellent job on it and he is VERY meticulous...

ARUN thinks that the velocity stack in place of the inlet pipe could pick it up as much as 50rwhp... If if does and it breaks 900rwhp SAE, ill be happy and won't mess with it any more. If not, then ill pulley down for more boost and let it eat.

I'm hoping to keep the small cam in it for stock like driveability and its great torque/response off boost. That's the plan for now.

 

Belt slippage usually shows on on the dyno graph with repeated peaks and lows, and you'd have black dust on the blower. I'd be curious how much add power you would pick up if the air/fuel above 5000 rpm was leaned up to 11.5/1 instead of the 10.5/1 you have, as it is running really rich. Bob

 

Hi Bob,

Bret moved the AFR around from 10.0 up to 11.5 I believe he said and it made no real difference in power anywhere... It didn't seem to affect anything. Same with the timing, 16-18* yielded the same HP although at 18* he was a little less confident leaving it there so it's back at 16*. He also richened the mixture back to 10.5ish so out under real load there is less chance of it leaning out.

IATs were around 90*. We are really hoping the 4" inlet pipe is the culprit here. Bret pulled the air filter off the pipe and it lost 19hp, he didn't try taking the pipe off of the blower. It's a long inlet pipe with a smooth 90* bend in it but some say they have seen major issues with having a bend of any kind in front of the blower so.... Hopefully that's the case..

(I doubt it's that simple though.....)

 

Very strange it didn't want to pick up any with more timing. The more timing we throw at mine, the more power it picks up(until 24degress then it levels off). What's the valvetrain set up on yours? 10.5 does seem on the rich side.

I'm still thinking its in the blower inlet or you just need to pulley down.

This is Jmuck from CF btw.

 

You shouldn't have any inlet problems with a 4" inlet pipe on a F1R. I have a 4 1/2" inlet necked down to 4" on my F2 and it will still pull to the moon. I would put a 4.00" pulley on it and let the blower eat. If it still didn't make any more power I would look for a boost leak or another restriction somewhere.

 

Here you can see the bend in the inlet... That's what we are thinking may be the culprit..



Not sure but.. Hoping that's what it is. I'm going to put the velocity stack on it and see if it helps. If not, then ill check for belt slippage again. Then go down to a 4" pulley....

We pressure tested the whole charge tube section up to 30 psi and had no noticeable leaks other then the screw holes in the volute (which we put set screws in to plug them)..

All of my charge piping has beads welded on the ends for the couplers to grip to....(although we still blew the charge pipe off once on the Dyno).


JMuck, not sure on the timing thing.. Bret played with it. At 18* he got 1 KR so he pulled it back to 16*. I don't think the power changed much at all.

As for the AFR, ill make pulls on the street to see what it's really at... Nothing wrong with 10.5-11.0 though.. No negligeable difference in power on the Dyno.

Eventually we will track tune the car for mph and read plugs and do it the real way. For now, I just want to see 900hp and drive it for a while.

 

I forgot that your on pump gas I agree that nothing is wrong with 10.5, just I've always gone for 11.8 and always had great results shooting for that. Don't get caught up too much in the numbers, make sure its safe and go see what it mph's and that you're happy with it. Can't wait to see it in person sometime.

 

Amazing numbers man Congrats on getting her done.
I'm sure Arun and Bret will get you 900rwhp but how does it feel on the streets I bet you were laughing from ear to ear

Vids?

 

I still havent driven it yet. I am going to pick it up from Bret this saturday. (he is 4hrs from me)... But yeah I can't wait to drive it. Its been 7 months since I've driven it.

I just miss having a sports car to cruise/commute in... I'm gonna daily drive this bitch for a while even...

 

Man thats great that you got the car back. Well I'll bet the loss in power from taking the filter off was probably heat being pulled off the condenser etc... NEVER pulled an air filter and lost power always the oposite. I had a hard 90 on my F1R right off the inlet because of it being an F-body. It won't be the size piping your using as I can see thats fine. The intercooer can be restrictive, but thats a easy check to do before and after log of the presure drop across the intercooler. I'm suspect of belt slip up top. when mine did it it took a LOT of pulls to see the belt dust finally and didn't really show up on the dyno llike it normally would. GLad you got it back on the road I know your happy about that. See you soon buddy.

 

If your going to be out this week end LMK!

 

Hey Jeff, what's up man?

I was going to try to get your number from Bill so I could pick your brain on a few things.

I MAY have it out Saturday night at Kemah IF I get it back from Dallas in time. I am heading to pick it up sat morning when I get off work at 4:30a. Gonna drive to Dallas, load it up and trailer it back. If I get home in time for the Kemah show ill be there...

I'd like to run a few things by you since you have been down this road. Maybe ill catch up with you then. Later bro.

 

Set up the chart in winpep so its a little easier to see/compare.



About to get the car over to G Force in the next week to experiment on the dyno and find the rest of my power...(hopefully)..

Also here is a vid of it in and running...

Put 120 miles on it today... 18 mpg and 60 mph 3rd gear burn outs on Nitto DRs... Not a bad day...

 

Very, very nice.

That power curve is awesome. Hope to see you hit 900rwhp.

 

Me too man...me too.

I got a velocity stack for the blower and gonna switch over to synthetic oil here before the next dyno session...

For an F1R and this engine combo, I'd expect no less then 900rwhp, especially at 19 psi or so...hopefully we can get it there.

I'm really looking for a 150 mph trap on a soft launch pass...but sometimes goals are tough to hit with stick cars and fragile drivetrains..

 

Nice numbers man. I've been talking to Bret for some time now maybe now that he's done with your car "finally" LOL, he will have time for mine. I live in El Paso and thinking of shipping it over there so he can tune it.