Okay here is what I got: 355 cid, speed pro 9.72:1 pistons, SDPC valvetrain modified vortec heads (64cc 1.94int 1.6ex) CompCams XE-268H Holley Stealth Ram intake w/adjustable fuel pressure regulator running 42lbs, LT-1 24# injectors, 58mm throttle body, '165 ECM w/MAF, 700R4 transmission w/Transgo shift kit, 2.73 open rear end in an '86 Camaro. Now the performance issue, the best time with street tires and the 2.73 rear end is 9.12 @ 79 MPH (approx) in the 1/8th. Dissatisfied with the time, but figured it had to do with the gearing, so swapped out the open 2.73 for a posi 4.11 and guess what! Best time was a 9.15 @ 78 MPH (Approx, Don't have time slip.) I know you are probably thinking "Wheel spin", but you would think my MPH would be higher. I was looking for about a .5 sec improvement, not identical times/MPH. I am very frustated because GMHTP did the HSR swap and was able to get 7.9X in the 1/8th. HSR anyway back to the drawing board to find out where I went wrong. Any and all help will be greatly appreciated, plus if anyone else is running a similar setup and could give me an idea of what you are running. Thanks in advance!

 

well from what i gather any intake swap isnt going to improve your times at all on the track. Unless you are running a bore/stroke motor or cam/heads or ll the above. I pulled a 8.9 running a posi 3:23 gear and stock everything else. Sounds like you need a dyno tune anyways to make sure the people that installed it tweaked everything just right

 

42# injectors seems awfully high for your application- I could be wrong though. Sounds like you need a good tune and a better torque converter if you don't have one. Also, did you research gears or just get the biggest ones you could find? Check over on the drivetrain/transmission forum and I'm sure they'll tell you what's happening regarding your gearing.

 

I'm running 24# injectors with 42lbs of fuel pressure. Just in case I worded that wrong.

 

yeah your fuel pressure is fine along with your injector size. I say get a dyno tune quickly

 

Do you have a custom chip or tune for that thing? If you don't, get one...you will be amazed at the difference.

 

I have been "trying" to do my own chips trying different spark advance tables. I am waiting on my Wide Band LC-1 to come in before I can really get a good tune. I am using TunerPro RT to modify my chips. I am confused on the "Power Enrichment vs RPM" and "Power Enrichment vs CTS" do both control WOT AFR or one or the other? I think my WOT AFR is part of the problem but with out a WBO2 I am shooting in the dark. Also I think my timing has some to do with it as well. Are there any "good" starter bins for the HSR?

 

I would like to see one those as well...

 

Yea...get the tune right and then let us know...once it is spot on...the power is awesome. Also, what is your max timing. HSR can handle a lot so I am at 34 right now and I plan to try 38 on 93 octane of course.

 

You referenced the GMHTP IROC running 7.9s - that run was made in 45 degree weather on street slicks. Still, that same car with a ported stock base, cleaned up SLP runners and a 2200 stall ran 2.0 60s, 8.7s@83mph, and 13.4s@103. Swapping out to a 3000 stall and heavily porting the SLPs let the car go 1.9 60s, 8.3s@83mph and 13.0s@109mph – blowing the slicks past the 60ft mark. Switching to the StealthRam, it ran 1.8 60s, 8.1s@87mph, and 12.6s@108mph with absolutely no hooking problems,, and is the main reason the ET dropped as much as it did. All these referenced ETs were in similar weather.

Saying all this, for comparison sake, the heads are different and the overall set up of the cars are different. The IROC is running a TH350 with a 2.52 1st gear ratio and 3.23 gears out back. The 1st gear multiplication ratio in the IROC is 8.14:1. You had a 8.41:1 first gear ratio with the 2.73s and now have a staggering 12.66:1 with the 4.11s. To get that ratio with a TH350 transmission, you’re looking at having to run a 5.00 rear gear. So,,, I think you had too little gear with the 2.73s to pull in down the track in high gear and now have too much gear with the 4.11s to fully utilize 1st gear – unless you have some serious hooking aides.

I’d also guess that you have a stock or close to stock converter. If so, even with the 4.11 gears and slicks, you would spend too much time in the RPM range that the StealthRam was not intended to run in. Consider a 2800 stall a minimum, 3000 – 3200 a better match with a 355. Plus, the gear recovery on the 700 trans is worse, meaning you drop to 54.5% of you’re RPM when you shift into 2nd gear. On the TH350, you drop to 60.5% (6400 x .605), which means you don’t loose as much RPM on the shift. Second to 3rd, you drop to 65.4% with the TH350,, compared to 59.5% on the 700. I held the IROC to 6400rpm in first and second gear to 6200 – if I short shifted from that,,, the ETs would take a nose dive – even with the better shift recovery rpm. Long story short, the TH350 lets you operate at a higher and narrower RPM band which compliments the HSR.

Comparison wise,, the box stock TFS heads on the IROC flowed in the 235cfm range,,, which is only about 10cfm more than what the Vortecs will flow on most benches – the exhaust head flow is much better with the TFS,,, so there might be .2 seconds in the heads. The transmission, stall, and gear ratio differences could easily add up to .5 seconds. I don’t know what exhaust you’re running, but the 3” inlet dual 2.5” exit UltraFlow muffler I’m running is worth a tenth or so over the typical dual exit Flowmaster. Pulleys, despite what some will say is worth .1 - .15 seconds at this power level, K&Ns and ram air was worth about .15 - .2 seconds with the TPI/SLP intake. I redid the Headman y-pipe to flow better, I’m running pro-magnum CompCam lifters set at 1/16 turn for preload,, and I built the engine myself and know for sure it was nuts on clearance wise,, it’s got a windage tray and a modified spring oil pump,,, all these things add up to make a little ET difference over a “typical” build. Add the potential differences that apply to you to the IROC’s 8.1s ETs and you might find that the 9.1 you ran is not as bad as you think,, or that the 8.1 the IROC ran is not as good as you think. It’s all about the total combination.

Also,,, I ran 44# pressure at the track with the 24# SVO injectors, which might flow more fuel than the LT1 24# injectors at the same pressure. It liked less pressure on the dyno, but the ram-air boxes must work once the car gets moving since it wanted considerably more fuel on the track for best ET. So,,, I’d also guess there is a good probability you’re running even leaner than you should be with a stock chip,,,, and it gets really lean at the top of the gears with “best set” pressure on the stock chip. Definitely check the color on the plugs until you get the WBO2 set up to see if you need to add more pressure until you can burn your own tune.

 

WOW!, and thanks for all that information you have definitely given me some things to think about. I guess you dont call yourself BadSS for nuthin!

 

Also def play with fuel psi.. mine has always liked 49-52..

 

Hrmm. i shipped a LC-1 to texas a few days ago. did you buy mine??

You're using $8D ?

Maybe I can help with the tune..

-- Joe

 

With your setup, I'd expect you to be lean based on the injector size and stock pressure. I'm not sure how well the MAF setup will adapt. But the WB will tell.
I agree also that the 4.11 might be a little much for your setup too.
3.42 or 3.73 is a good compromise when running a 700r4.
Your 268 cam is all done by 5500 max. Comp has/had a dyno curve on their site for it. The intake used for the test had very similar runner length to the HSR.

The PE vs CTS is for WOT sort of. It compensates fuel based on engine temp.
The PE vs RPM is extra fuel based on RPM also just like the CTS table.
The code adds both values together and then does math to adjust the fuel.
Exactly when PE fuel is added depends on the TPS position and RPM.
Some SD cals have a MAP requirement also. I don't recall if the MAF bins do off hand. (an airflow table)
There are tables for all this kind of stuff.

 

Maybe I did go a bit steep on the gearing, but hopefully I can deal with it or switch to a TH350 or even better go to a T-56. All in good time though. Baby steps.

 

For all that are keeping up with this thread what do you think about this cam? Also I do plan on finding a 2800 to 3200 stall converter. Hopefully the stall will help with my disappointing e.t.'s. Carry on with the suggestions this is great stuff for everyone.

 

Do the converter swap and tune first - then determine if you need to swap the cam. I shifted at 6400 rpm with marginally better heads and a similar cam (2-degrees advanced - 108 intake centerline),,, so I don't think the cam you're running now is a problem - plus the 113 spread listed above would make less power at the shift recovery point than what you have now. If funds allow get a good converter that will let you lock it up under WOT.

 

Thanks again BadSS, I take it that the IROC in GMHTP was or still is yours? If it is/was it was my inspiration on intake choice, it just so happened I had already ordered all the components for the engine prior to reading the article, so some of my parts did not match exactly. I am still trying to find some slicks. Suprisingly though I did not have wheel spin off the line (maybe because of low stall speed ~1700) but I did have wheel hop. I think another problem might have been the fact that I had a different tune than with the 2.73 gears (should have mentioned that above, but just remembered).

 

i personally dont know jack about EFI's and own a TPI. I got my 4:10 gears in on my 700R4 and love them. You really need a stall to match the gears and your powerband. Knowing the HSR makes it so your peak RPM range reaches 5500+ then id stick with a 3500 stall and make sure you have some drag radials to keep the tire spin away

 

Wanting to have my cake and eat it too, I was wondering if a 2400 stall would be a good compromise if I wanted to retain some driveability.

 

og God know dont go that low of a stall. That's not much better than a stocker. Get the 3000 stall and with gears it will be perfect

 

Dang,, 1700 stall,, no wonder it didn't run a well as you hoped. I've still got the car,, thinking about selling it. I've got a 1985 Monte Carlo SS (BadSS tag - hence the screen name) that I bought new and lately I've been working on a maxed out 406 with a modified FIRST injections intake to top it off as funds allow. I bought the IROC for the wife, but made it a little faster than I originally intended it to be and she's afraid to drive it,,, and I'd like to have the funds from it to finish the SS off at show quality. Anyway,,, the 10" TCI thats in the car flashes a little past 3000 rpm and it is totally 100% drivable in all conditions at all throttle positions. I ran that same size stall in the SS when it was my daily driver for about 10 years,, don't worry,,, just get a good name brand converter and you'll be fine - you get what you pay for. Go with a 10" with a 2800 - 3200 stall range or you'll be sorry (you don't want to compromise on the converter). I have run expensive ($650 - $800 - for a TH350/400 trans) 3500 - 3800 stall converters on the street without any problems,,, but you start having to put out the cash for them to give you the flash speed and still be efficient enough to run on the street as a daily driver. I tell you man,,, you're going to crap a brick going from a 1700 stall to a 3000 range stall!!!!!!!!!!!!!!

 

Well fellas I'm one step closer to "gettin there" just got my WBO2 in the mail, checking it out now. It may be a few days before I can install it, but looking forward to seeing whats happening with my AFR. Still looking for a 2800-3200stall converter though.

 

Just wanted to tell you that your trap speed is related to your Hp. So, if you do not increase your Hp, your trap speed should not change. At least thats true for the 1/4 mile, I am assuming that its true for the 1/8 mile also.

The ET is too dependent on the start, therefore ET is a bad predictor of Hp.