Dyno Numbers in on a Gt40p setup...

mr_woodster

Active Member
Jul 28, 2003
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Riverside, CA
Well I'll start off and say, Though the numbers displayed here are not awe inspiring, they are not exactly bad. Here is the combo

Rebuilt long block (.030) with Gt40p heads (no porting)
Trickflow (TFS) stage 1 cam with stock (non roller) rocker arms/springs
Trickflow street heat intake
Mac cold air intake
Underdrive pullies
BBK shorty headers
Stock (read: very restrictive) 4 cat (california nazis) H pipe
Smog pump still hookedup
AODE
Dyno tune (with some flaws still to be worked out)
Stock MAF/injectors


dynopic.jpg


The 4 cat h-pipe and aode are deffinatly working against larger numbers here. But this is a daily driver and the Torque curve is pretty sweet. The temps at the time of the Dyno run were in the mid 80's maybe low 90's , this is at sea level.

What do you guys think? should the dyno tune resulted in more power from this combo?
The A/f ratio was in the mid 12's on the best run of 231.2 hp and 265.8 tq.

Am i seeing vavle float at the end of the run near 5,500rpm?
 

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Those numbers still seem really low...Paul or Gcomfx dynoed his car with almost the exact same setup as mine with stock heads and cam and put down 239rwhp. Even with cats and AODE i would have thought you would be in 255range and without cats maybe around 265-270ish.
 
I bet the stock cats are KILLING you. Got a lot of miles on that pipe? How about the factory catback, is that still on?

While it is lower than I would have thought it is not all bad since you have the AODE.

Let's see what others have to say but I wouldn't have expected too much more...
 
Looks about right to me.

A tune will wake it up and shake out about 10 rw. You could try retarding that cam a couple degrees to help you out on the top end. It's time to step up to 24lb injectors but the stock MAF will still serve you fine.

I know what valve float is but I don't feel comfortable enough to diagnose it so I'll leave that for someone else.

Adam
 
This currently is the only print out i have. I most likely will be going back after i pass smog and put the other *ehem* H-pipe back on. He also mentioned i should replace the o2 sensors. So we will see what that nets me hp wise.
 
The stock stamped rockers are garbage as well, with that cam, and those heads you are doing no justice by having non roller. Those numbers look just about right to me, a couple more things will wake it up considerably. I would do the following:
1. put your other h pipe back on. 2. 24# injectors. 3. roller tip roller rockers. 4. get a little head work done, by head work I mean new valves springs retainers etc (this is not absolutly needed but if your getting float this will stop that) and If you can afford it, a nice port. This should put you right about 260+ hp and over 300tq. I got 263 hp, and 305tq on my cobra when it had stock heads, and a e303 cam, with a few other goodies that you already have.
Did you have Steve tune it or just a dyno run?
 
An auto will absorb more power but from the things I've seen ......
I couldn't give you a rule of thumb about the loss as I've not been able
to find any kind of consistency when they are used :shrug:

The squiggly lines could be
valve float
tire spin
ignition

The results seem in the ball park to me :)

I'd upgrade the mid pipe as the OEM pipe is very restrictive

You need more fuel :Word:

I'd do in tank pump, inj, & meter

Yes the OEM rockers are kinda clunky :(
but
I'd be willing to bet you would only find only 1 or 2 rwhp with 1.6 rr's

Not much gain for all the money they cost IMHO :shrug:
so
I'd hold off on them for later ... if even then :shrug:

Grady
 
FWIW- I had a VERY VERY sim. setup (and have one just a hair diff. now).

With factory stock gt40 heads off a 95 cobra, TFS1 cam, ported stock lower, pullies, 14*, and 24lb inj. with a C&L so they would work. I put down like 230-ish and 285-ish rwhp with 30+% comp. loss in a cyl. in the stock shortblock with a 5spd car. I would think if kinda fair comparo...7cyl. to an AOD...not too bad but room for improvement.

Right before I popped the cyl. I ran a 13.5 at 102 the only time I ran it at the track with this setup and had a 2.4-.6 60ft (really bad for me).

With the mods in the sig in the beginning of Aug. I put down 251rwhp and 287tq. 99* with 50-60% humid. and only 30* total timing. IIRC one guy that day picked up 9rwhp when the humid. droped 10% and temps went down to the mid/low 90's. With the factory 4 cat H-pipe as well.
 
Did you have Steve tune it or just a dyno run?


Steve Tuned chiped/tuned it to make it run a little more nicely with the cam. The computer just didnt like the cam at idle at all!

I see quite a few you saying the 19lb injectors are starving it, but the AFR is in the 12's, so am i missing something? I've read the air meter is good to ~ 300rwhp along with the throttlebody.

The roller rockers would be *neat* but i dont see them netting anything exceptional except abit more vavletrain noise.

I figured these numbers are unique as i havent been able to find any gt40p /AODE numbers posted, yet.
 
One thing to note about roller rockers is that you can rev the engine a little higher. I noticed a good difference at the track with roller rockers. Of course I also went with a higher ratio rocker which affected the overall lift of the valves. But, a smoother running valvetrain will net more power due to efficiency of the roller versus slider type fulcrum.
 
Well I'll start off and say, Though the numbers displayed here are not awe inspiring, they are not exactly bad. Here is the combo

Rebuilt long block (.030) with Gt40p heads (no porting)
Trickflow (TFS) stage 1 cam with stock (non roller) rocker arms/springs
Trickflow street heat intake
Mac cold air intake
Underdrive pullies
BBK shorty headers
Stock (read: very restrictive) 4 cat (california nazis) H pipe
Smog pump still hookedup
AODE
Dyno tune (with some flaws still to be worked out)
Stock MAF/injectors

The 4 cat h-pipe and aode are deffinatly working against larger numbers here. But this is a daily driver and the Torque curve is pretty sweet. The temps at the time of the Dyno run were in the mid 80's maybe low 90's , this is at sea level.

What do you guys think? should the dyno tune resulted in more power from this combo?
The A/f ratio was in the mid 12's on the best run of 231.2 hp and 265.8 tq.

Am i seeing vavle float at the end of the run near 5,500rpm?

Your dyno numbers are about what I'd expect with your combo, and are not bad when you consider that the drivetrain HP/TQ loss in an AODE GT is about 22-24% (it's only ~13% in a 5-speed manual). You could do better though.
As you already know, the stock catted H-pipe and sloppy-shifting AODE are hurting performance, so you could do yourself a favor by installing a performance catted H-pipe and rebuild the AOD with a shift kit. If you don't already have a 3.73:1 ring & pinion, do it 'cause you'll love the result.
The stock valve springs are pretty sturdy and your dyno curves don't nosedive at the top end (the dip at 5400-5500rpm is the tranny shifting up) so I don't think there's any valve float. The wavy line from 5000rpm upwards is more likely to be from a small ignition misfire; maybe the plug gaps are too big.
 
Mr. Woodster.........I am in the process of putting together a similar combo (GT40p and AODE). However, I will be running the stock cam with 1.7 rockers/full exhaust and the Cobra intake that I have. I need to send the heads off to a machine shop for mill/springs etc., but after that I should have it together for some dyno time. I will get back to you when I've got some numbers for comparison. BTW, how did the BBK headers fit?

Thanks,
James
94 GT Vert AODE
 
Hey James, The bbk Headers fit perfect with no clearance issues to speak of. Do note that the spark plug (i think its 7) will require you have a cut torex headed spark plug socket for changing in the future. I also recomend 90* boots for the spark plug wires for good clearance.

Other than that the swap is straight forward (note your air injection tubes will no longer bolt up to the back of the heads , as they eliminated those ports).

TIP: come up with a mounting scheme for the air tubing and such to pass visual smog requirements. I passed this way with flying colors. The new head design is much cleaner burning!
 
Hey James, The bbk Headers fit perfect with no clearance issues to speak of. Do note that the spark plug (i think its 7) will require you have a cut torex headed spark plug socket for changing in the future. I also recomend 90* boots for the spark plug wires for good clearance.

Other than that the swap is straight forward (note your air injection tubes will no longer bolt up to the back of the heads , as they eliminated those ports).

TIP: come up with a mounting scheme for the air tubing and such to pass visual smog requirements. I passed this way with flying colors. The new head design is much cleaner burning!

Is your setup for a street application? Im debating between gt40ps and a set of thumper's E7s for a mild 260rwhp daily driven build. Because the gt40ps are a more efficient design, would they net better economy for street driving than the stock motor? Just curious, its not that big of a deal but it would be cool.
 
I see quite a few you saying the 19lb injectors are starving it, but the AFR is in the 12's, so am i missing something? I've read the air meter is good to ~ 300rwhp along with the throttlebody.

Two things to think about here :)

1) The dyno does not demand as heavy of a load as the street does
so
The inj's will be worked harder ... on a daily basis :(

2) You got an auto trans
so
The inj's will be asked for more when comparing rwhp to a stick car :(

I'll just leave it at that :)
cause
On more occasions than I can remember ... I've stated my preference of ....

Tuning the pcm at OEM fuel pressure and using meter/inj's sized according
to combo requirements ... like Ford does it

as opposed to ......

The mechanical method of tuning with small inj's and elevated fuel pressures

I'm not saying you are not getting by :nono:

I am saying you are playing a game of ... calling it close :D

For me ... that is ... T O O ... close for comfort :eek:

Grady
 
Hey James, The bbk Headers fit perfect with no clearance issues to speak of. Do note that the spark plug (i think its 7) will require you have a cut torex headed spark plug socket for changing in the future. I also recomend 90* boots for the spark plug wires for good clearance.

Other than that the swap is straight forward (note your air injection tubes will no longer bolt up to the back of the heads , as they eliminated those ports).

TIP: come up with a mounting scheme for the air tubing and such to pass visual smog requirements. I passed this way with flying colors. The new head design is much cleaner burning!

Hey man where in riverside do you live ? I live in moreno valley I'm trying to see how many other stangers live in riverside