Thanks for all the replies! Hopefully it is just in the tune. When I had it dyno tuned before I still had exhaust leaks and a no MSD box yet. I should have waited until I got things sorted out. Because my headers/y-pipe/ORP are all ceramic coated, they welded the wide band O2 bung into the front of the cat back exhaust. It's hard to say how many joints in the exhaust were leaking before that point. It's hard to get that ball & socket setup on the MAC's to seal real well. The race version of the long tubes w/slip on connections and band clamps should fix those problems.

Yes it is. The vacuum modulator only takes away the control of the hydraulic pressure. My shift points will still be controlled by the PCM. The electronic control has trouble holding hydraulic pressure above 6000 rpm. The vacuum modulator should fix that. My trans isn't in the best shape but it really shouldn't be the main cause of my slow times. It probably will get built by the end of the year. I plan on spraying the car once I get my N/A problems figured out. I don't think the trans will like that too much.

Welcome to the board. I sent you an email.

 

Scott,
I can't remember if you told me or not, but what kinda numbers did the car make? APE tuned it, correct? 3750 really isn't all that bad for a vert, my t-top car weighed in at that w/ me in the car last year.

Also, if you do end up getting rid of that Digital 6 I may be interested in it.

 

The 3750 was a guess. It's probably more like 3850 but I didn't want to overstate it. I've added an 8 point chromoly roll bar, custom chromoly subframe connectors and a heavy *** BMR adjustable torque arm. Weight reduction consists of spare tire & jack, back seats, A/C compressor, lightweight carpet & front sway bar.

It was tuned at Speedworks. It wasn't ready for the dyno. The dyno graph shows the engine breaking up between 5800-6100 rpm. Greg thought it was due to blowing out the spark because of no MSD.

I can't afford to spend another $500 on a dyno tune so I'll be spending $50 on a PCMforless tune that I can upload myself with LT1 edit. From there the fine tuning will be done by a fellow local enthusiast who knows his way around an LT1 PCM. My dyno tune money is going toward the long tubes instead.

We'll have to talk about the digital 6. Dennis already called dibs on it but if he changes his mind, it's yours. Assuming I do wind up switching to the Delteq.

 

you can go dyno tune a car with exhaust leaks meaning more than one. if youve fixed them your car is running rich. you need to get all the exhaust leaks fixed and get it retuned

 

I think the times are pretty good considering the weight. What were the weather conditions when you ran those numbers? With my car, my times will drop down into the 12.6s to 12.8s in poor weather conditions. We all know lt1s hate heat. Tuning will definitely help also.

 

Yes it is. The vacuum modulator only takes away the control of the hydraulic pressure. My shift points will still be controlled by the PCM. The electronic control has trouble holding hydraulic pressure above 6000 rpm. The vacuum modulator should fix that. My trans isn't in the best shape but it really shouldn't be the main cause of my slow times. It probably will get built by the end of the year. I plan on spraying the car once I get my N/A problems figured out. I don't think the trans will like that too much.

-- hmm.. interesting.. were do they sell somthing like that?

 

Transgo sells a kit. It's around $125. I bought mine from Ramchargers. You could contact Transgo and they could tell you who a local distributor is for you.

You could also buy a high end built up 4L60E trans. Pretty much anybody making race prep 4L60E's switches them over to a vacuum modulator. FLP level IV and up transmissions are vacuum modulated.

You can do a search here or at ls1tech.com for more information.

 

I've built 4L60Es running 11.0's that still retain the computer controlled pressure. Vacuum modulators are akin to putting a carburetor on an LT1. People do it just because they don't understand what they're working with.

Frank

 

Your converter is way too small... especially for that tank of a car. Jump up to a 3600 converter (at least) and put the car on a diet if you want some better 1/4 times.
Steve...

 

From what I understood, they are changed mainly to avoid the problem big converter cars(3x multiplication) have with shifting into second.

 

You're right on the money, Eric. That's exactly why I'm converting. The "program" fixes Ed Wright, PCMforless and others provide only work some of the time. From what I understand, the vacuum modulator works all the time. It also helps smooth out the bone jarring part throttle shifting.

 

The temperature was probably in the 60's and the DA was probably under 1000.

 

The plan is to change my Vigilante over to a 3200 or 3400 (more likely) stall. I just need to get the vacuum modulator kit installed. I probably won't switch it until I pull the trans for a build up in the fall (or sooner if needed). It only 60 ft's in the low to mid 1.7's now and it should be solidly in the low 1.6's.

 

that trap speed is pretty impressive......what kinda weight reduction do you have? Also i am guessing you are still on a 10 bolt? Any dyno numbers?

 

That car seems to me the car is bad in need of a converter and a 4.10 gear, with those two things and some bite look for some low 12's
I would go a 3800 converter and a 4.10 if it was mine.


David