Yeah, finally got to the track with my siamesed base on, and yes i'm a little dissappointed.

Previous best run in the spring was a 14.10 @ 95.3 on a 1.87 60'
Same track, similar air, siamesed base was 14.23 @ 94.7 on a 1.94 60'

I am not ready to declare defeat though and more than evever i think there is more left in it. Here's an example of how to overthink dissapointing results...

1- Different tires. In the spring i was running dunlop SP5000s, real street tires. I have a set of BFG drag radials now. I have to wonder if i'm not giving up some power across the board due to the sticky tires. Also i was only running 26psi, since the track was busy i didn't want to 'waste' runs going up in smoke off the line. I want to re-evaluate that idea and start from a higher pressure to really see how it hooks.

2- Wrong chip. I'm still running the same chip i was in the spring basically, including a timing curve that i optimized for the stock converter. Only change is i'm running 4' less timing across the board cuz thats how it ran well in the heat of summer. I'm going to play with some timing curves on the street and see if i can find any SOTP snap left in it.

3- Wrong chip. I think my fuel is way off too. My 60's got incrementally better as i leaned it out, even after my MPH went down. LTR fuel is probably completely wrong for a siamesedbase. I mean, it sounds like a completely different engine, makes sense that it's PE fuel demands would be different. Also going to try playing with this on the street and see if i can find any SOTP here.

4- IAC. My IAC is completely dead at the moment. Since the IAC acts as a throttle follower, this would limit total airflow and therefore possibly power across the board.

5- Shift points. I was shifting 5500/5000 for my first few runs. On my last run i shifted 200rpms lower on both shifts and i lost nearly a mph and a tenth. Of course the barometer also went up almost an inch between runs, so it could have been that i was suddenly running leaner as well. The more i screw around on the streets though, the more it seems to like shifting higher. Still though, i cant see this thing really wanting to rev that high on a stock cam and heads, siamesed base or not.

Oh well. I guess it wouldn't be much fun if this thing always cooperated with me. Hopefully i can find some magic just playing with it. I will be mad if i can't get this thing to run a 13.99 before winter though...

 

Sorry to hear about your disappointment. I have a set of AS&M runners I was going to put on a siamesed base in my car. I also have a Vigilante 2400 tc and some headers. Haven't done the TC because I am a bit intimidated by the labor involved, especially since my car is a vert. I would love to hear some better news on the siamesed base, it would be much cheaper than an Accel base. How far into each runner did you siamese? Good luck and keep us posted!

 

glad you like your runners bob

 

I was thinking about doing that to my intake, but I think I will wait until I have some # for the new motor before I do it.
Keep us post on the how you do with tuning that car Ed.

 

Hey ede,

Wouldn't you want to go lower on your tire pressure to give you more sidewall wrinkle? Also you didn't mention sizes. Is it possible those slicks are a little taller than your street tires. I read your previous post about siamesing the intake and I thought that getting it to rev higher and make better power at the top end was the point so why lower your shift points? Wouldn't you shift at a higher rpm to take advantage of extra breathing of your manifold?

 

I want to run more tire pressure because i don't think i need all the hook i have. After all, i did run 1.85 on real street tires, and lots of 1.8s. Tires are the same height, even verified.

As for why not shifting even higher. Well it's something i am experimenting with, but keep in mind we're still talking about a stock cam and head car here. A couple hundred RPMs might still be in it too.

Another thing i just realized today is. Back in the spring my forced TCC lock was set at 94. Right before i crossed the line. Now it's set at 90, a little distance out. Off the top of my head i think it saves about 200rpms when it locks. But maybe that extra top end efficiency ain't where it's at. I'll prolly crank up the lockup speed and test it off and manually to see what it does.

 

If you have a 305 in that vert those runners would probably massive overkill on it. Considering how easy they are to swap, it'd be worth trying back to back at the track to see what it really does though.

My base is siamesed halfway through, right to where the PCV holes come in the floor. I made a good size slot, but didn't go so far as to completely flatten everything as some pics i've seen have it.

As for performance, upon further review, i'm actually only down 0.6mph, which could easily be explained by 26psi drag radials. So even if it's equal in power right now it feels alot better. Once a cam goes in it it should be a whole new game too. With a revised timing curve and maybe a tune-up on the brakes so i can hold it better i'm sure i can get the launch back...

As for the converter...you'll be damn happy when you do put it in, i can promise you that much

 

I say try moving your shift points up 500 rpm or so. I put a cam in when I siamesed my base ~3" or so. Anyways, the fastest times I ran were at the highest I could shift at 5500 rpm, (rev limiter)compared to 4800-5200rpm with the stock stuff. Another thing added SLP runners and lost .5 sec, put the stock runners on and got my times back. This was all with a SLP chip for a stock engine and a MAF car 5 speed. I never got more speed(power) out of my car, but SOTP was great regardless.

Stock intake/cam 14.6 @96 mph
siamesed base 2032 cam 14.4 @96 mph
SLP runners added 14.8 @93 mph
stock runners again/lower fuel pressure 14.3 @ 96.8 mph(higher alt. track than other runs) ~1000-1500ft

all 60' are in the 2.2- low 2.3 range

 

Ed, about the BFG DR's. I put mine at 20 psi and did about a 5 sec. burnout after driving through the water, I didn't notice any wheelspin at the track (on the street I have a lot even w/ the DR's). I had 1.730 60's on my 2 best runs. The above seems to have worked well for me.