Chassis Dyno results: Comments?
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 3,281
Likes: 6
From: NC USA
Chassis Dyno results: Comments?
Put the car on a chassis dyno this weekend and did 3 pulls. The best pull was the first one with the
following results at ~5800RPM:
RWHP=303 RWT=415ftlbs Fuel mixture=12
The dyno tech told me that I needed a better cam to 'wake up' the 454's hp and told me that the
torque would improve also and air/fuel mixture #s were good already. Since this engine is supposed
to have 425hp at the flywheel, even allowing ~18% for the driveline/IRS should be about 350hp
which is what I expected to see. Why would the hp be so low? My current 'mystery' hydraulic flat
tappet cam is mild since it has no lopey sound and idles smoothly at 750rpm
My engine details minus cam info are in my sig.
following results at ~5800RPM:
RWHP=303 RWT=415ftlbs Fuel mixture=12
The dyno tech told me that I needed a better cam to 'wake up' the 454's hp and told me that the
torque would improve also and air/fuel mixture #s were good already. Since this engine is supposed
to have 425hp at the flywheel, even allowing ~18% for the driveline/IRS should be about 350hp
which is what I expected to see. Why would the hp be so low? My current 'mystery' hydraulic flat
tappet cam is mild since it has no lopey sound and idles smoothly at 750rpm
My engine details minus cam info are in my sig.
Burning Brakes
Joined: Aug 2000
Posts: 984
Likes: 1
From: Cincinnati OH
Re: Chassis Dyno results: Comments? (Marks69BB)
Since this engine is supposed to have 425hp at the flywheel, even allowing ~18% for the driveline/IRS should be about 350hp which is what I expected to see. Why would the hp be so low?
[Modified by Vince Ivanc, 4:50 PM 11/5/2001]
Drifting
Joined: Jul 2000
Posts: 1,861
Likes: 1
From: Bremerton WA
St. Jude Donor '09
Re: Chassis Dyno results: Comments? (Vince Ivanc)
We always expect more than we end up with.
That said, have you checked the basics? Do you have exhaust that is up to the job? Is your timing correct? Are you getting proper timing advance? Is there a restriction in your system somewhere? Maybe a gasket that somehow shifted during assembly? Is your induction system up to the task of supporting the airflow you need?
You really have to look at everything sometimes.
Good luck!
Cory
That said, have you checked the basics? Do you have exhaust that is up to the job? Is your timing correct? Are you getting proper timing advance? Is there a restriction in your system somewhere? Maybe a gasket that somehow shifted during assembly? Is your induction system up to the task of supporting the airflow you need?
You really have to look at everything sometimes.
Good luck!
Cory
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 3,281
Likes: 6
From: NC USA
Re: Chassis Dyno results: Comments? (CHarris85Vette)
I guess what you are telling me is that the HP claims of GM for the new vettes is net hp since there were two Z06s there also. One was a modded 01 that went 374hp/368torque and the other was a stock 02 that went 353hp/347torque which has 405hp on its side emblem. This versus the older BB 427 vettes with claims of 400 and 435hp that was apparently gross! :cry
Anyway, I think it's time for a cam since everything else is the 'good stuff' and the exhaust will be changed to Hooker sidepipes this winter! :smash:
Anyway, I think it's time for a cam since everything else is the 'good stuff' and the exhaust will be changed to Hooker sidepipes this winter! :smash:
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 3,281
Likes: 6
From: NC USA
Re: Chassis Dyno results: Comments? (71coupe)
71coupe - CR is either 8.5 or 9 and I burn 93 octane but it won't lug or ping even on 87. The engine has the open chambered heads that allow for lower compression. I'm wondering how this engine could be built while still being able to run on 93 octane since I've heard that it can be done.
[Modified by Marks69BB, 5:37 PM 11/5/2001]
[Modified by Marks69BB, 5:37 PM 11/5/2001]
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Re: Chassis Dyno results: Comments? (Marks69BB)
Mark-
A 454 can take a bigger cam than a smaller motor & still be driveable.
The limitting factor on the cam would be your compression. A bigger cam keeps the valves open longer & it tends to bleed off compression, causing a power loss.
If you have 9.0:1 c/r, look for a cam with no more than 230 deg @ .050 for hyd & 235 deg @ .050 for solid. That will wake up your motor with a nice choppy idle. Your 454 could take more if it had more compression.
Also, look for a cam with a wider lobe seperation. They usually run from 108 deg up to 114 deg + . This may help for the lower compression.
[Modified by 71coupe, 4:14 PM 11/5/2001]
A 454 can take a bigger cam than a smaller motor & still be driveable.
The limitting factor on the cam would be your compression. A bigger cam keeps the valves open longer & it tends to bleed off compression, causing a power loss.
If you have 9.0:1 c/r, look for a cam with no more than 230 deg @ .050 for hyd & 235 deg @ .050 for solid. That will wake up your motor with a nice choppy idle. Your 454 could take more if it had more compression.
Also, look for a cam with a wider lobe seperation. They usually run from 108 deg up to 114 deg + . This may help for the lower compression.
[Modified by 71coupe, 4:14 PM 11/5/2001]
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