535 on the chassis dyno
 

Got my 69 firebird on the chassis dyno with the new 535 and tiger heads. This is more of a street car than race car as it has no roll bar, 3500 converter,3.50 gear,and the engine idles down pretty good. I feel the engine is a little weak because it only puts 553 HP and 491 LBS tq. to the ground. My question to ya'll is who has chassis dynoed their street/race car (with resultant 1/4 mi times)so I could have something to compare to? My goal is to be able to run a high 9 sec. 1/4 while looking and sounding stockish (on the outside). It has 3" exh with 4 mufflers to keep it quiet. The intake is a sheetmetal piece that I made and posted to be critiqued and based on the responses it may be my problem. I will post a dyno sheet later today. This car also weighs 3735 with me in it.

Steve

Don't be too disappointed in the numbers. There are too many variables. My chassis dyno numbers made me puke! And they weren't as high as yours. I had a mismatched converter and it blew right through it. Ending up in the nines with a quality converter. You are going to need a roll bar for sure and that's gonna add some weight, not Sure of your intake but at that weight with 350 gears I think you are going to need 750-800 at the crank to crack the nines. Motor should have the nuts to get you there. You'll just have to fine tune it.

Thanks Mystic, I'm somewhat encouraged. I'm figuring I need another 50-80 hp to reach my goal and I know the heads are not restricting me. We put a vacuum gauge on one of the pulls to check for a carb/intake restriction but the gauge was reading about 1 inch vac. So I think I'm ok with carb (1050 Dom) and intake.

Steve

What brand chassis dyno?

Excellent numbers.

My TA put down 420/440 ish to the wheels and ran 10.90's @ 125. (3.42's 3500 converter that was going bad) The same combo in a GTO with a better converter went 10.20's.

Dynojet 248x

Thanks David, I was really hoping for 600+ but I am not going start changing parts for it.

Steve

Converter, tires, the dyno itself all come into play, don't look at the numbers, use it as a tuning tool. We use it to find the timing the motor likes and to test changes, not to make predictions with. ;)

The MPH at the track will tell you what power you're making. If the ET doesn't match, play with your suspension and gearing/converter.

the best there is...


post your combo & dyno graph so i can share a 540ci with you ...

excellent reply David,but not according to some believe that its a "static test"....

http://www.hkmotorsportsdynoshop.com/

I had a combo that made 505hp to the rear wheels and ran 10.40's.

I think it will go 10.0's or 9's right off and steady high 9's with finding the right sweet leave spot and chassis tuning.

What changes did you make on the dyno?
Timing?
Carb cfm and/or jetting?
Peak HP rpm.
Peak torque rpm
That is the purpose and can get you where ya need to be.

Best pull so far with the TA is 520/632. At 3970 its best pass has been 11.02 @ 124.8 with a 1.608 sixty. That was in good air with my old intake. Havent been to the dyno with the new Kasse/Wilson one yet.

Plan to go back to the rollers in the next couple of weeks.

calculator
 

using a Et calculator. 3735 lbs with 553 hp at the rear wheels looking right at 11.0. Think with proper chassis set up and right converter may hit mid to high 10's.

http://robrobinette.com/et.htm

Allways Engine dyno a new combo,the chassis dyno will throw you curves.Bill C.

OK, I have a print out of run # 6 and a graph of the last pull #11. Power seems to fall off when a/f drops into the mid 12's and falls off when below 40 degree total timing. In a day or two I will try 42 degrees or will advance till power drops off. The 1050 dom. 8896-1 is a challange to tune because I still want good idle and street manners. I just removed the intermediate air bleeds and the curve straightened out and part throttle smoothed out. I have 90 front jets w/ 3.5pv and 98 rear jets w/ 2.5pv. 53 hs air bleeds front and back.
The engine is like this:
535 ci, ported tigers 440-450 cfm, jesel shaft rocker 8:1, 11:1 compression, 30cc dish on the BRC pistons supplied by P-Dude, 264-270 duration 790 lift solid roller, ( it actually Idles down pretty good), sheetmetal intake built by me to fit under the hood, 2" headman headers into dynatech mufflers, to a 3"crossover then to 2- 3" magnaflow muffs and finally all the way out to the rear bumper with 3" tails so its quiet, MSD probillet and 6AL box, hughes 3800 stall converter, T-400, 3.73 12 bolt rear that will soon be replaced with a 9" and 3.50 gear.

Engine and Chassis dyno's are excellent tools, despite being "static" tests. They really help cut to the chase with basic tuning, and when you swap parts around really show us how they work in comparison to each other and it what part of the rpm range, etc.

I've back to backed dozens of intakes, scores of carburetors, moved cams around, lashed solid cams all over the place, and even tested 3 cams in the same engine. We also dyno just about every single engine that leaves here (engine dyno). The dragstrip is the real chassis dyno far as I'm concerned, and making the numbers always shows how the entire combination actually uses the power it has on tap.....Cliff

What size tire are you running. I ask because the mph vs rpm is low for a 3.73 gear. You may be blowing right through that hughes converter.

At 11.1 cr with 440-450 cfms,with the right cam and manifold it should be around 900HP on engine dyno.Bill C,

Well I think the engine has it in it I'll just have to find it. I will go to the local 1/8 mi, Sumerduck Raceway, and put the motor to work.

Tires are 255 60 15 BFG radial t/a

I might talk to Bob C. or Dave Wilcox and see if the have a tiger intake I could borrow to test against my sheetmetal intake. These guys are more local to me. I appreciate any input you guys give me.

Steve

That 1050 carb is too small for that motors intake needs, and that 1" of vac proves it.
you will pick up 30 HP with a 1250 carb thats jetted right!

Call me. Yes we do have intakes in stock. I bet that your home made intake is part of the problem. If you don't make intakes for a living you are wasting your time. It is an art to get one to flow as needed.

Based of the mph on the dyno sheet, at 6000 rpm you have 14% slip. That's a lot.

Tin, it certainly feels like it wants to leap off the dyno. The converter was tightened up a bit from the 4000 stall that it was, but I think you bring up a good point, something for me to investigate. I will just leave it hooked up to the dyno till this weekend and try it again. How much slip is acceptable at top end?

Steve

x2 just was wondering why his chassis dyno #'s so low with his combo. I figureing he would be around 750 to 790 at the rear wheels.

The smart move would be to call Ceralli Comp. if you have questions about how to improve it.

Brian, I agree but my 455 went 465 rwhp and ran 10.90. I'm sure I will eventually get 560+ rwhp and at least be able to cover a 10.20 1/4 Mi. then drive it home listening to classic rock. As of right now I have +90 hp and + 50 lbs tq from the old combo. Will that get me to a 10.20? Time will tell for sure. The torque peak was 4950-5000 rpm and the HP peak was 6200 and very flat, which I think is good for overall averages. The split between the HP and TQ was about 1200 rpms. As I'm gathering all this data I'm trying to figure out if I could go up to a 1250 carb, as mentioned earlier, and /or is the intake doing its job based on cam dimensions, cubic inches, HP and TQ peaks. I feel i'm an adaquate tuner but I also know i'm amongst real pro's and will listen to sound advise.

Steve