Just finishing up the rebuild on my 88 vette, got offered an accel intake. I planned on doing the siamese treatment to mine, which would be better? Accel or the siamese intake. The motor was bored 30 over and I installed the crane 2032 pwr max cam. Presently I planning on running 1.6 RR, and my heads were CC'ed and came to 53cc.

Thanks in advance

 

Accel!!! The accel w/o being touched is better than a ported stock base.

Here are a couple of shots of my my accel next to my stock one.

 

I second the Accel :yesnod:

 

Three strikes accel's got it.

Much better than anything you can do to the stock base.

 

What's the going price for the Accel? the person that owns it, left it with the machince shop that did my short block? What's a fair price for it?

Thanks

 

Accel.
BTW, check all threads in that puppy before installation. Perfect time to chase and repair any damaged threads. Don't ask how I know to give that advice :crazy: :lol:
price? uh.....
maybe begin negotiations at $200.00? complete SR(they include the accel base) have gone as low as around $600ish sometimes around here. I guesstimate average is $800 for the 3 pieces.
Consider smoothing/polishing the interior of the intake some too. Fuel dropping out of the charge due to lack of turbulence is not much of a factor since the fuel is shot out of the injector downstream.

 

i think a siamesed base will flow more air and make more power than an unported ACCEL piece. the whole concept of siamesing the manifold runners is that each intake port will now be recieving air from TWO runners instead of one. this allows for much higher rpm power. there was a dyno chart on Thirdgen.org from someone who did this to a basically stock 350 TPI that showed his peak torque #s at 4800rpms, and peak hp #s at 6800rpms! he siamesed about 5" into the base, this is a little extreme for stock cam and heads, however. i plan to dyno test my car in its current configuration, then siamese my base manifold about 3" in, and dyno it again (with track times also) to see the results. id like to see the #s from a basically stock L98 (like mine) with just an ACCEL or similar aftermarket base installed for comparison

 

Vic'89 added an Accel base with stock runners and got no gain; after he installed my AS&M LT runners he picked up about 15hp.

My stock base is siamesed 1" deep and I have prior dyno pulls; just haven't found a dyno shop local to get another set. Then I plan to open it up another inch or two in. BTW, my L98 is now pulling strongly into the mid 5k RPM range, though gets flat by 5,800rpm.

 

I'll expand a little more on the above statement. With the Accel base + AS&M large tube runners + ported plenum , I only gained .15 second in the 1/4 mile.

For the price of the above mods, there is not a big bank for the buck. Total cost was about $750.

Siamesing a stock base would be a better bang for the buck (free).
65Z01 has the siamesed base + stock runners and is running as strong as I am.

Vic

 

it seems to me siamesing the runners would make some real HP. it's a tad hard to grasp how doing the base on the stock runners is worth power only becuase they are limited by the runner. i easily can see how a larger runner would benifit from the cut base & reworked exit. as it sits the only runner on the market that gives a person some play room to tweak with i've seen is the SLP. yes they really suck stock but the castings are so thick you can port them however you'd like. here's a close up pic of a ported mouth slp runner, there's still quite a bit more i could do here if i wanted to. you guys think there's more power taking the siamese down another inch or so :D

 

The idea behind the siamese base is 1) to provide a pseudo plenum if the base cut is large enough and 2) to provide effectively twice the runner flow volume (there are now two runners joined at the intake base) of nearly the same runner length.

If you siamese the runners you lose the low end tuning and low end torque as shown in TPIS "Insider Hints".

Hopefully retaining most of the runner length retains more tuning to retain low end torque, while providing more air at high rpm.

Since I have an A4 the dyno operator started the pull at about 3,200rpm in 3rd gear so I won't be able to get a direct measure of low end torque. However I did see a slight increase in short time at the strip which I interpreted as some loss of torque at launch. With my higher stall (2,000rpm) TC that is no longer an issue. Of course if I did heads, cam and headers low end torque would also increase to offset any loss from a siamese base.

I paid $100 for used intake and runners and about $50 to have them cleaned up in a shop plus maybe another $50 in porting tools. So compare this $200 to say $800-$900 for a BM (or SLP) base and LT runners; if it works (I want to see the dyno curve), is a very cost effective way to improve the intake on a TPI car.

If you take that runner siamese cut down deeper it should help top end breathing, at the expense of some low end torque since you are raising the tuned frequency.

 

whenever the machine shop finishes up what's in my sig i'll be able to dyno it & provide some numbers. however my heads and cam aren't exactly stock so it's a little loaded for a base comparison.

 

I have one of DRM's intakes that seem to be just as good as the Accel base....

 

For now since im low on money, I'm just going to siamese my base manifold and get a better pair of runners and siamese them as much as possible. Then get a high converter and change my shift points, then I'll be able to pull over 5,500 RPMS if I go into my base about 3 inches.

 

if you want to siamese your runners the SLP's i posted a picture of are $269 from summit racing, also fit what you want with porting the easiest as they are a cast 1pc unit with a LOT of extra metal.

 

Thats some nice looking work GTSyellow. I ported my plenum too but left the Accel LT runners alone.

 

I probably will end up buying the SLP runners, like you said there is a lot of metal to port. The edelbrock base too, I heard that they make the base for TPIS, TPIS just ports it a bit more. I can port it myself, no need to spend the extra money. Looks like ill be buying my exhuast runners and base soon, can't wait to take it to the track then! :reddevil


[Modified by Red91Vette, 12:10 AM 7/25/2002]

 

i'd buy whatever lower base you get the best deal on, the accel and TPIS bases are cast a little better than the edelbrock but like i did & you mentioned you can port them pretty easy.

 

I have one last question about porting my base, well two. One, when you remove the base how hard is it? I heard you have to take the distributor off and putting it back on can be a PITA! Second question, I have speed density, and if modify the intake to rev to say 5,800 RPM's, how well the speed density take that? I heard mass air is a lot better with mods, would I need to get a special chip? Where would I get one? If I didn't do anything computer wise, what would happen to the car? Would it not run right or not start? I can't wait to do this mod, then I will be able to actually run from a role and beat the newer LS-1's maybe! Thanks in adavance. :chevy

 

speed density is fine as long as you don't change the cam, they are really picky with vac changes. i managed a best of 13.2&107 on my stock engine, cam, heads before it blew with bolt ons. you'll still shift about 5500rpm however, it will go to 5800 but you'll be faster 5200-5500, i was able to beat stock C5's left and right before i got into the engine, the only internal mod was roller rockers.