Based on the 3 people so far that I’ve seen posting before and after TRACK times on this and other boards, it does not appear this mod is all it’s cracked up to be. All three slowed down or had near identical ets. Has anyone actually gone to the track and been pleased with the “after” times from this mod? Emphasizing TRACK, or at least before and after g-tech times,, anything more definitive than the butt-o-meter. If so, please share the results, cause it looks like it’s 3-0 against the mod right now.

 

Before I was shifting at 6500 which I found out I shouldnt and ran a 14.3 after I did it, I was shifting at 5400 and did the intake and ran a 13.8, and gained a 10th on 60ft too. Just to let you know, you could totally hear The cam even more after I opened it up.

 

Sweet! You can hear your cam.

 

Thanks for the reply juicin. I'm not sure if I can count the 1/4 times as a positive "after" since you were shifting the non siamesed base at 6500 and now shift the siamesed base at 5400 - as you stated you were WAY over revving the "before". However, the 60 ft time decrease (picking up .1) is note worthy. What's your basic combo? Was it the same track and similar weather conditions?

[This message has been edited by the roc (edited September 27, 2001).]

 

try changing the cam when you siamese. higher rpm airflow has to be complimented by a cam that has more lift and duration.

 

so,, we tah did,,, have you siamesed a base and changed cams?

 

Yup it says "Wheres 87Zya? I need to roast him"

 

So no one has any positive track or g-tech times from siamesing the base?

 

track times hell, look at the dynos madmax did. the improvement is obvious.

 

mike davis' dyno results were not so good after the mod and slowed down from it - that's in the same thread - or at least the link to mike davis' page was. One good dyno - one bad dyno.

I'm also still trying to figure out how max was pulling 6300 rpm out of a completely stock TPI (with EGR wall) that everyone else on this board claims is a 4500 rpm limiter.

 

Give me about 3 weeks, I'll have a post on how well the siamese works on a minor bolt on '89 5 spd 305 tpi 3.42 gears< i run 93.65 mph right now(headers, muffler, cat, Al driveshaft), I'm getting a chip(slp) and a homemade ram/cold air. After that I'll put in my siamesed base and tell you how much i gained.

 

Thanks Beast - everyone would appreciate it I'm sure

 

interesting, i didnt see the bad dyno. does anyone know how much he siamesed his intake compaired to madmax's?

 

I didnt see the 1/4 times on Davis' page before, but notice he lost .17 off the line, that will affect the ET, looks like the MPH is the same (pretty close anyway), and keep in mind he went from a ported Edelbrock (aftermarket) to a siamesed one. I'd like to see results with the same 60' time. He also didnt take out as much as I did. If any of that matters, I am not sure. It definitely worked on my application. Theres not enough information yet to decide where it might not work, how much needs to be taken out, etc. I could take my car to the track sometime but the track it was originally at I cant go to anymore and that was a hot day as well when it was there. I know the car is faster, theres no question about that. Hopefully more people will post their results and you can decide from there.

I dont know if I'd say Davis' dyno was "bad", he did gain a little power if you look at the average at the bottom. Average is what you are looking for, as long as the range matches the car and its a wider powerband. I know he didnt get anywhere near the increase I did. IIRC he went about 2", I went alot more than that.

[This message has been edited by madmax (edited October 04, 2001).]

 

just looked at the post again, you notice mike did do that to a edelbrock high flow base. not good i guess. the only benefits seem to be from the restrictive stock manifold where it needs the extra airflow.

 

I’m with Madmax in that Mike’s dyno comparison did not look “bad”, but it did start well after his stall rating at that time. Plus Mike’s engine was hurt sometime along the way and I’m not sure if he knows exactly when it started it’s demise – it could have started before the siamesed base track times or dyno sessions? I hope I’m not speaking out of turn for Mike. I think he’s got the engine back in shape, and he’ll probably post new times on his site pretty soon. From what I can tell I think he likes the siamesed base mod.

I will reluctantly say I knew two guys that siamesed their stock bases about 14 years ago. One fried #7 running it lean (the rest of the pistons looked OK), but who knows what he did,, or didn’t do. The other swapped to a carb in disgust when the mod slowed him down. I doubt either really tuned on it properly,, and I know both were running the stock chip,, but so am I right now. In their defense they did have a good knowledge of basic tuning principles. My own very limited experience with our IROC and my first fairly modified EFI car,, based on a series of test with a set of SLP runners, yield me to believe runner length is no free lunch. I mean as far as I can tell from my limited testing I’m fairly certain my combination would slow down with a siamesed base. Go figure?

 

As mentioned, my engine has been an ordeal
this past year.

-I've come to like the siamesed base. It
was nice to run the 1/4 mile and actually
continue to make power down the track and
not watch those carb cars catch you at the
end

-I'm now running again with all 8 pistons
and a Vig2800 converter and running 12.3@109
times.

-I still contend that the siamesing will hurt
or kill low-end power and it's only the
addition of the higher stall that makes it
worthwhile for me on the street.

( I shift 1-2 at 5800rpm, 2-3 at 6200 and
cross the line in 3rd at 5800rpm..)

I hope to re-dyno the rebuilt motor & Vig
later this fall..

mike



------------------
My Z28, ZZ4swap, TPI EPROMs

 

Thank Mike.

We all appreciate the amount of time and effort you spend on your page to help inform the 3rd gen crew. I appreciate the reply to this post and it looks like you've got one mean TPI.