TR Custom Parts
Mark Hueffman - Owner
- Joined
- May 25, 2001
And he was out driving it on the street tonite!
Made my first 8 second pass today on the first time out in 10 years
- Thread starter turbobitt
- Start date
Whats the difference between race weight and street weight?
We now know how much Allan weighs.Whats the difference between race weight and street weight?
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Ya, I'm not in the best shape of my life. Age is catching up and metabolism slowing down.
http://turbobuick.com/forums/threads/who-is-this-tb-com-member.379204/
I been trying to quantify how the cam change I made after the dyno effected power. The last dyno session at the same boost level I ran the car at made a little over 900 HP. The turbo was starting to run out of breath. I also had the turbo upgraded to a billet wheel so that could have some influence. The injector DC was exactly the same between dyno and track. The ambient conditions were no where neare as good at the track. The manifold temp was significantly higher, and I took some timing out. It is not an apples to apples comparison but my best guess is that it made at least the same power with worse ambient conditions.
Allan G.
You will have to use a cam with Donnie specs to get the big increases your want. I put small cam numbers in the SIM and still made very decent power, between a 218 cam and 235 cam maybe 40 hp difference max. The power is mostly in the head and turbo, unless you do a huge cam change you might not see big differences.
norbs said:
The turbo used/ boost pressure and compression ratio definitely have a huge effect on the power band. The cam timing,LS, and CR are just as important as the duration at .050. At his current boost the engine would be much better off at 10-10.25:1. It will take boost in the low 40's to get the most out of it with the cam and CR he's using.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
As stated above, you are comparing at differences between 218 and 235 cams with probably low lifts. Both of these selections are most likley to small to work within the efficiency range of the stage 2 heads and show any considerable gains. Based on what I learned, I wouldn't run anything smaller than 235 cam.
I would predict that I had at least 40 HP gain. Based on comparing ambient conditions of the dyno and track, and cosidering that I pulled timing. I would have expected the car to fall short of an 8 second pass.
If you were to use some of these HP calculators, it would say that the car is making roughly 1000HP to the tires. This would be a 100hp gain over the dyno. I don't really trust the HP calculators but still can't resist looking at them.
Allan G.
I have no idea how accurate the SIM is when I just change the cam duration, lift etc, but I have the compression set at a static 9:1 I;ll see if I can post up the graphs. Bison may have a good point, but as we raise compression we get less volume of fuel in the cylinder, but more pressure, kind of a trade off for a street car , but higher boost and lower compression will make more power, so Allan, time to crank the boost up, but then your turbo will be out of its efficiency range. maybe............
To run the pressure ratio needed to maximize the compressor wheel he's running his 9:1 CR is right on target for a gasoline application. It will likely take boost in the low 40's at sea level with minimal pressure drop at the inlet to get the most out of it. Everyone thinks about the compression stroke when you start talking compression ratios. The ex stroke and over lap needs to be considered. The effective operating rpm will be widened and raised with a higher CR if the cam lobe/timing is optimized. So you could take the engine further even though the cyl pressure will limit the amount of boost that could be run for a given octane. The engines mass efficiency increases quite a bit with a higher CR just from the further minimized time in the dead flow zone when both valves are open at the same time and the piston passes tdc.
That is quite interesting I guess once he turns it up it should wake up.........I guess I will have to do the same boost level to get some power out of it on the 3.8 stage project I'm building.