Cam Combo Test SR20 272/272 vs. 264/272

[imaboa]

I am swapping around cams in my car, and will be posting up some dyno results as I make changes.

A little about my car and the current set up: Stock RedTop SR20740cc HKS Side Feed Injectors300zx Fuel PumpSheet Metal Intake ManifoldPorted Cylinder Head, Upgraded Springs/RetainersSynapse Turbo Top Mount ManifoldGT3076R 0.63A/R Stainless Steel Tial HousingSpearco IntercoolerBC 272/272 CamsHaltech Platinum Sport 1000 Stand Alone ECU

When I originally pieced the car together, I didn't have much of a goal in mind, and came across some used parts here and there, so my set up isn't really that great. So, not suprisingly, I'm a little disappointed with the power delivery of the car. My goal is to help the mid-range response and make the car a little more suited for open track events.

Right now the car has a decent power band from about 5k to 7k-ish. I'm not really turning that many rpms, just because the motor has about 100k miles on it, and I am really not up for a motor build at the moment. Everything is done overly-conservative, but, for me there's no worry that its going to come apart, and I'm cool with that.

Anywho, to get this party started, I've posted dyno charts for the BC 272 intake and 272 Exhaust cam. [IMG]I am swapping around cams in my car, and will be posting up some dyno results as I make changes.

A little about my car and the current set up: Stock RedTop SR20740cc HKS Side Feed Injectors300zx Fuel PumpSheet Metal Intake ManifoldPorted Cylinder Head, Upgraded Springs/RetainersSynapse Turbo Top Mount ManifoldGT3076R 0.63A/R Stainless Steel Tial HousingSpearco IntercoolerBC 272/272 CamsHaltech Platinum Sport 1000 Stand Alone ECU

When I originally pieced the car together, I didn't have much of a goal in mind, and came across some used parts here and there, so my set up isn't really that great. So, not suprisingly, I'm a little disappointed with the power delivery of the car. My goal is to help the mid-range response and make the car a little more suited for open track events.

Right now the car has a decent power band from about 5k to 7k-ish. I'm not really turning that many rpms, just because the motor has about 100k miles on it, and I am really not up for a motor build at the moment. Everything is done overly-conservative, but, for me there's no worry that its going to come apart, and I'm cool with that.

Anywho, to get this party started, I've posted dyno charts for the BC 272 intake and 272 Exhaust cam. The plan is to swap in an HKS Step 1 264 Intake cam to see how that affects the power band, and then possibly the 264/264 Combo.

Power and Manifold Pressure for Current Set Up:http://www.sixsigmadyno.com/ch...I.jpg

Power and Torque for Current Set Up:http://www.sixsigmadyno.com/ch...Q.jpg

[imaboa]

Here are a few photos of the car and the engine bay.







I just finished up the 264 Intake Cam install. Without touching the tune, the car started a little quicker, had a little less vacuum at idle (about 11-12inhg vs. 12-13inhg with the 272/272 Combo)

I'll get the car on the dyno tomorrow and do some steady state tuning to get the majority of the fuel and timing maps done.

Modified by imaboa at 8:55 AM 10/31/2009
Modified by imaboa at 8:59 AM 10/31/2009

[imaboa]

I had every intention of re-tuning the car and finishing the test up today, but the garage door to my shop is bound up. I am waiting on someone to come replace it, so I can get the car on the dyno.



Anyone have a similar car set up?
Modified by imaboa at 8:26 AM 10/28/2009

[pauliedrft]

this is very interesting

[kentuckyslider]

I had the same turbo with a .63ar housing, cast log mani , 2.5" dp , very conservative JWT rom tune, and 21psi peak boost. I also had tomie 260 procams with 12mm of lift and I loved them. Here is my dyno. Looks like I made power a little earlier then you. Why outside of the cams I don't know. Here is a link to the cams and they are $125 cheaper now then what I paid for them. http://www.phase2motortrend.com/tomponfors1s.html

[kentuckyslider]

After looking at the pics your sheet metal intake is killing your TQ. I would go back to the oem intake if it was me. When you say "track days" do you mean drag, autoX, or drift. The only way I would keep that intake is for drag use. I switched from the oem intake on my car to the isis freddy knock-off and gained about 10whp up top and lost over 20ft/lbs of tq and alot of area under the curve. My car trapped 2 mph faster but with slower times in the 1/4.

oem intake+20psi+good tune on your stand alone=30-40 more lb/ft of tq and much more area under the curve on your setup. I am a big fan of the oem intake unless you are doing a serious drag setup with a 35r and trying to make north of 500whp.

I know our dyno numbers are very close and yours may even be better considering I was on a dyno jet and you were on a dyno dynamics.

[kentuckyslider]

oh yeah, get you some greddy RAS and set the rev limit at 7800rpm. It will do that all day long with the upgraded valvetrain and pull all the way to redline.

JWT sets there redline at 7850rpm with nothing but rocker arm stoppers on oem sr heads and they are very conservative tuners. I ran mine like that for almost 2 years before i upgraded cams without any issues. Bounced it off the rev limiter over 200 times at the drag track coming out of the burnout box.
Modified by kentuckyslider at 5:25 PM 10/30/2009

[DuckyD]

In for results.

[imaboa]

I've got the rocker arm stoppers and the redline set at 7800. I don't think I pulled the car that far in the charts I posted since I was only worried about the lower rpms.

Youre right about the RAS, those are a musthave.

[imaboa]

I'm trying to post some pictures here without using a link. Can't seem to do it.

How did you get your dyno chart to show up in the post?

[imaboa]

Ok. I figured out the image thing. I'll post up some pics in just a few.

[imaboa]

Ok. So here's a dyno graph comparing the 272/272 Cam Combo to the 264/272.

I made 3 pulls and didnt do any tuning since the clutch started slipping around the middle of the pull. I went back and looked at the logs for my 375hp pull, and think thats probably where the "steps" in the power graph were coming from also. I didn't want to make any more pulls and totally kill the clutch (I needed to drve the car home last night...)

Anyways, I'll post up some more graphs once I put a new disc in it, but the end result was about 600rpm quicker spool up. At 4200RPM the car picked up about 50hp. The top end power was killed by the slipping clutch, so my test is a bit inconclusive, since I wanted to see what the low end vs top end power trade-off was going to be like.



Here's the datalog showing the clutch slip. On a "loaded" dyno like a Dyno Dynamics, the speed that the car accelerates is controlled by the retarder on the dyno. The car, no matter what gear its in or how much power it makes accelerates in a linear fashion, with the ramp rate controlled by the dyno. This being said, you can spot clutch slip in a datalog if the graph of RPM vs. Time is non-linear (the thin line in the datalog is RPM, the thicker line is manifold pressure). In the log below, this starts happening about 7 seconds into the pulls.




Modified by imaboa at 9:04 AM 10/31/2009

[DuckyD]

Anyways, I'll post up some more graphs once I put a new disc in it, but the end result was about 600rpm quicker spool up. At 4200RPM the car picked up about 50hp.

Picked up 50hp with the staggered cams, or with the matching cams? Which color lines represent what? (pink vs green)

[imaboa]

The staggered cam picked up power on the low end.

The Pink (376hp peak) is the BC 272/272 setup, and the Green (302hp peak) is the 264/272.

Its hard to tell what the peak power loss with the staggered set up vs. the 272 setup is since the clutch was slipping.

I know that stock cams on any of the GT28s makes 340-350 on this dyno. So I can't imagine the loss would be more than about 10ish at peak power.

[shift_SRDETuser]

I use

The staggered cam picked up power on the low end.

The Pink (376hp peak) is the BC 272/272 setup, and the Green (302hp peak) is the 264/272.

Its hard to tell what the peak power loss with the staggered set up vs. the 272 setup is since the clutch was slipping.

I know that stock cams on any of the GT28s makes 340-350 on this dyno. So I can't imagine the loss would be more than about 10ish at peak power.

I use some greddy staggered 256/264 easy cams and it keeps my vtc. I hit close to those numbers around 340 wheel hp and 311 ft pounds on the top end only difference in the mid my graph was shifted up so the mid range was more.

[imaboa]

What kind of dyno did you see 340hp on?

A Dyno Dynamics Dyno typically reads about 13% lower than a DynoJet.

375hp on a Dyno Dynamics is going to equate to about 425hp on a DynoJet.

340hp on a DynoJet would be about 295hp on a Dyno Dynamics.

The Dynapac Dynos read pretty close to the Dyno Dynamics.

[shift_SRDETuser]

It was almost a year ago but I believe it was a dynojet chassis dyno. The one up in the air?

I run a gt2871r so with the gt30 400whp is very possible I just did not want to fry my bottom end. At 18 lbs I am in the mid 300s on a dynojet so that makes me happy. I never knew their was so many people making dynometers?

[DrifterProdigy85]

Youll find the power of the straight 272 setup is gonna come after 7500rpm. The 272 intake is gonna hold the valves open longer letting the head breath so much better at high rpm compared to the 264 intake. Its not a true comparison without having the RPM to back up what the cams are made to operate at.