Battling backpressure at RPM with AMS-1000

[Dusty Bradford]

I don't see a 224/224 pulling very well above 7,000 rpm on 274ci.

 

[turbobitt]

Motor is 9.5:1 compression and the can is a 224/224 with 112lsa. Nothing exotic

As for peak torque, when cal was here doing the tuning we had to abort the last run because my fuel pump couldn't keep up so I do not have a perfect No. But it was still pulling hard and the slope on the dyno sheet was still increasing steeply at 6100 rpm for both hp and torque.when at the track I feel it still pulling at the higher rpm. I know for certain it pulls hard up to 7000, does it pull hard from 7000-7500? That's hard to say, but when looking at the mph and driveshaft speed on the log, they are increasing at the same high rate.

If I am out of compressor I would have to step up to a 88mm or something wouldn't I? Going to a larger 1.44 A/R wouldn't do anything if this is in fact a air consumption issue and not a back pressure issue, correct?

There are some really nice 82 billets or MFS out there begging for your combo like yours!!!
AG.

 

[lazaris]

Your boost changes are directly related to your rpm. As rpm goes up so does the BP. On the gear change the RPM drops and so does BP.

 

[Chuck Leeper]

Your boost changes are directly related to your rpm. As rpm goes up so does the BP. On the gear change the RPM drops and so does BP.

Hi Ralph!!

 

[gnxtc2]

Did you ever run the car down the strip? Or is this dyno results?

Billy T.
gnxtc2@aol.com

 

[forcefed3.8's]

What 76 are you running, Billy?

 

[lazaris]

Hi Ralph!!

Hey Chuck. How are you?

 

[gnxtc2]

What 76 are you running, Billy?

A GT42 that is 5-6 yrs old. Ran a 5.18 @ 138 in BG a few weeks ago. I ran 8.19 @ 165 (trans slipping) last year at BG.

For the past 5-6yrs, I never changed anything on the motor. I kept working on my suspension. So far, I went from a 8.6 to 8.19 (1/4 mile times) just tweeking the suspension. You can have all the HP, but if you can't use it, what good is it.

Billy T.
gnxtc2@aol.com

 

[forcefed3.8's]

Thats what i thought. Are you willing to share your rpm range?

 

[forcefed3.8's]

That is very impressive.

 

[gnxtc2]

^^^^^Thanks

I also want to add....

You need to get on the track and test, test, test. You need to write down what worked and what didn't, keep a log. There is no magic or secret pixie dust. You need seat time on the track to be comfortable going down the track.

A dyno is fine to get baseline but it doesn't substitute the track/seat time. A dyno is a tuning tune, that's all.

I know guys that have ran their quickest time and we're curious what the HP was. They strapped the car down on a dyno and the tune smoked out the shop but ran fine going down the track.

Billy T.
gnxtc2@aol.com

 

[karolko]

Did you ever run the car down the strip? Or is this dyno results?

Billy T.
gnxtc2@aol.com

Hi Billy,

I have very little seat time in the car, maybe 10 runs this year, but i get the car into to do a 8.91 at 151 with a 1.28 60' and that was at a 8.0 psi launch so i really feel that the car has a lot of potential to run considerably faster. The screenshot of the log was infact from that 8.91 pass.

If i could run 8.19 i would be happier than a pig in shit!!!

I have a Precision 7675 GT 42 style with the 1.28 A/R housing and billet wheel, ball bearing...all the wizzy good stuff.

Billy is right, seat time is a must and learning what the car can and cannot do is important. I am at 3500' elevation so that doesn't help me at all. That said, i think that i can still improve on my 60' and if i can get the boost pressure to stay constant throughout the run, and not drop down at the higher RPM's, then i will shave some time off the E.T's.

From what i have read, our turbo cars do not react much to little cam changes, so i wonder if going down that route would be beneficial.

Billy, i too am curious what you spin your motor to, just for comparison purposes, but i understand if you want to keep your cards close to your chest.

 

[forcefed3.8's]

Do you have a cam card? It sounds like you have the same 224 lobes I am running. What heads are you running?

 

[ttypewhite]

Our setups are not far off of each other. But I don't see a 224 cam making power past 7,000rpm. Have you played with your shift points? Like shifting the car at 6,600rpm from 1-2 and 6,600rpm from 2-3 and letting it ride out the back door? Just curious, what ignition system are you using? and what plugs and gap are you running? Your spark can also be limiting your potential. 28psi is about the limit I can get out of my MSD Digital 6. I would need something much stronger like a 7 series to allow me to throw more at it, but for my purposes and the amount of driving i do on the street, The MSD Digital 6 suits my needs.

 

[karolko]

Our setups are not far off of each other. But I don't see a 224 cam making power past 7,000rpm. Have you played with your shift points? Like shifting the car at 6,600rpm from 1-2 and 6,600rpm from 2-3 and letting it ride out the back door? Just curious, what ignition system are you using? and what plugs and gap are you running? Your spark can also be limiting your potential. 28psi is about the limit I can get out of my MSD Digital 6. I would need something much stronger like a 7 series to allow me to throw more at it, but for my purposes and the amount of driving i do on the street, The MSD Digital 6 suits my needs.

I am using a FAST XIM igintion and i gap my plugs at 0.021. AR3932.

As for shift points, no i have not played around with them just yet. As i said before, very little seat time in the car so far.

Adrian

 

[karolko]

I called Comp this morning and received my cam card from them. Is anyone still interested in knowing the specs?

 

[turbobitt]

I called Comp this morning and received my cam card from them. Is anyone still interested in knowing the specs?

Or at least the lobe numbers and LSA. May look like 3192S/3192S R112
AG.

 

[karolko]

4871S /4871S R 112.0

Is this what you are looking for?
224/224 cam
LSA: 112
Intake centerline: 112

 

[turbobitt]

4871S /4871S R 112.0

Is this what you are looking for?
224/224 cam
LSA: 112
Intake centerline: 112

Yup. Are you running this as a solid or Hydraulic ? I think you would do better with the 224 3192 lobe on a solid FWIW. The 3192 lobe after being ground on a Buick core will be about as aggressive as a really good solid roller cam would be and has a lot more area under the curve for more flow.
The 4871 Lobe is from the Extreme Street roller family and seem these run as hydraulics or tight lash solid. They are not super aggressive but do maintain valve train durability.
AG.

 

[karolko]

Sorry, forgot to mention that: It is a solid roller. Does that change your opinion?