Dynoed with 3.10 upper and 8 pound lower ..Lost over 30RWHP WTF!!!

[F8l Vnm]

Well guys I finally got a chance to dyno my 03 cobra with the 8 pound lower and new 3.1 upper and barring nothing else that went wrong I lost more than 30 RWHP...
I did take off my Mafterburner and Pro Flow mass air unit which I dynoed before with but other than that the car was the same.
My tuner and I are almost positive thats thats too much speed for the Heaton and we are over spinning it to hell.
My dyno graphs is really UGLY.
I get peak tq at 3600rpms which was 526 and it just takes a nose dive from there.Nothing like the straight tq line we are used to seeing from the roots blowers.
And Hp climbs its way to 461RWHP and starts to fall of pretty bad at 5400 Rpms and over ..
So my dyno numbers were 460RWHP and 526 RWHQ. But UGLY AS CAN BE...
My old numbers were 491hp and 498tq.
So what do you guys think ???Too much for the stock heaton ?
I'am just hoping that thats what it is and nothing major .
Anyone with suggestions , comments or anything...:shrug: :read:

 

[vector]

Originally posted by F8l Vnm
Well guys I finally got a chance to dyno my 03 cobra with the 8 pound lower and new 3.1 upper and barring nothing else that went wrong I lost more than 30 RWHP...
I did take off my Mafterburner and Pro Flow mass air unit which I dynoed before with but other than that the car was the same.
My tuner and I are almost positive thats thats too much speed for the Heaton and we are over spinning it to hell.
My dyno graphs is really UGLY.
I get peak tq at 3600rpms which was 526 and it just takes a nose dive from there.Nothing like the straight tq line we are used to seeing from the roots blowers.
And Hp climbs its way to 461RWHP and starts to fall of pretty bad at 5400 Rpms and over ..
So my dyno numbers were 460RWHP and 526 RWHQ. But UGLY AS CAN BE...
My old numbers were 491hp and 498tq.
So what do you guys think ???Too much for the stock heaton ?
I'am just hoping that thats what it is and nothing major .
Anyone with suggestions , comments or anything...:shrug: :read:

What are you useing to tune the car i dont see a chip in your sig
if it was the mafterburn and you took it off then I can see why you lsot HP

also unless that eaton is ported you are Heating it up alot tahts the other reason for loss in HP

 

[HIGH ROLLER]

Were both dyno runs done on the same dyno?

 

[F8l Vnm]

I Use Shwan @ So. Cal Diablo sport.
He has tuned it before and I wouldnt trust anyone else.
I did take the mafterburner and the maf of because I hated the idling of teh car .
But you guys that the mafterburner would make me lose over 30rwhp???

 

[Rwick7]

Your spinning it too much...all you need is a 2.80 upper...anything more and your pissin in the wind unless your gonna put some kind of ice box on the car

 

[ALA G8R]

Originally posted by StlBlack03
Your spinning it too much...all you need is a 2.80 upper...anything more and your pissin in the wind unless your gonna put some kind of ice box on the car

Agreed. Try the 3.1 with a 2 or 4 pound lower and I bet you get that some of that HP back. Then get an SC porting to realize hp gains on top of that.

 

[Silver03]

Originally posted by ALA G8R
Agreed. Try the 3.1 with a 2 or 4 pound lower and I bet you get that some of that HP back. Then get an SC porting to realize hp gains on top of that.

With this config, should a tune still be done? My other mods are listed below. I'd really like to get some more power without f'ing with the computer.

 

[Rwick7]

If you go more than a 3.4 pulley I'd tune it. Try a 2.93 and a predator, the predator is a little more warranty friendly.

If you haven't rode in a pullied car yet...do that first...and then there will be no turning back :beer:

 

[Snkbyte]

I had the same problem with a 2.8 upper and 4lb lower. You just can't spin that eaton that much. It takes alot of hp to spin the blower.


Will

 

[Silver03]

Originally posted by StlBlack03
If you go more than a 3.4 pulley I'd tune it. Try a 2.93 and a predator, the predator is a little more warranty friendly.

If you haven't rode in a pullied car yet...do that first...and then there will be no turning back :beer:

I have a DeltaChip waiting for when I do pulley it. I just haven't worked up the balls to more than likely void my warranty. How warranty friendly is a Chip?

 

[vector]

Might not have been the mafter burn messing up the car but the MAF you put on it

 

[NeedForSpeed]

since this topic is at hand......

My old set-up was a 2.8 upper and 4lb lower.

With stage 3 crower cams (484\484 280\280), ported head and a ported blower............. along with running the cooling mods like a heatexchanger, ice box, apten head cooling mod.... radiator etc.....

What is the optimum set-up?

I'm keeping the 4lb lower, but was thinking of downgrading the upper pulley size.

What would be a decent upper in this case.... 3.0 3.10 2.93?

I haven't given this much thought yet since the pulley and tune are the last things for me to worry about at the moment.

 

[F8l Vnm]

I'am just keeping my fingers crossed that thats all it is .
I will prolly re-dyno again with just a lower 8 pulley and hopefully get my power back.

 

[Shoey]

good luck

B

 

[whitey03]

By changing the lower that much, you're really just changing the trq numbers. HP numbers won't change that much or, in your case, dropped a little.

Try a 2 or 4 lb lower.

Should give you much better results

 

[F8l Vnm]

I originally started with the 8 lower and stock upper , so I'am going to keep the 8 lower and now with the stock upper again.

 

[kilroy]

Metco lower only

I was thinking of doing exactly that. Larger surface area on the stock upper pulley and the larger lower- btw, did you swap in the alternator pulley when you did yours or just the crank?

I have recently driven a mildly pullied car and must feed the need...

 

[F8l Vnm]

Yes I did change the Alt pulley as well.

 

[JPKII]

Just some numbers:

All blower RPM figures calculated at 6500 crank RPM

stock upper and 8 lbs lower = 17006 RPM
3.10 upper and 8 lbs lower = 20024 RPM
3.10 upper and 6 lbs lower = 19080 RPM
3.10 upper and 4 lbs lower = 18032 RPM
2.8 upper and stock lower = 17700 RPM

IMHO the 3.10 and 4 lbs lower may be the optimum setup.

If anyone is interested I made and excel spreadsheet where you can calculate and graph blower RPM vs. Engine RPM for any given pulley combo. It also has a calculator that can calculate gearing for your rear end. Send me your e-mail and I'll send it to you.

 

[BALDSNAKE]

Refrig. being installed tomorrow

You got it....too much heat for the Heaton. Changing to Apten, Gords HE with dual fans, Fluidyne radiator...all with Evans NPG+ coolant. Running 2.93 upper/6# lower. Will post new numbers later in week when I get a re-tune. I'm not the first to do this. There have been posts on other forums getting 530/530 with this cooling set up.