what would one of these manifolds do for me over stock? any improvements?

 

yes, it would def be better then the stock intake base.

 

would it free up a couple HP or what?

 

Yes, but it wouldn't be worth the work unless You were already digging deep into the engine.

 

Incorrect. The BIGGEST bottleneck in the entire motor would be the base manifold. I replace the stock manifold with the Edelbrock, large tube runners and ported plenum with a 52MM T/B and no other engine mods except headers and it put out 239RWHP and 309RWTQ. 100% stock tuning, heads and cam also.

That is 48HP and 62TQ over stock. Not bad, IMHO.

 

where are some good runners that would go with it to get the hp and torque your talking about?

 

would i be better off with a 52 or 58 mm throttle body?

 

The base can be made to flow well with porting, I am amazed at how nasty and full of casting flange my base is. If you don't want to do it yourself send it off and have it extrude honed. You also have an 86 305 TPI that has an amazingly tiny cam, change that first it's where your real bottle neck lies in that engine.

 

Neither, stick with the stock 48mm and port the plenum really well.

 

Even the best possible ported stock manifold is still bad compared to an unported ACCEL or Edelbrock manifold.

Do not waste money extrude honing the stock manifold. The cam is a big detriment, but the best cam isn't going to do squat with out a better intake tract.

 

ok, so when i get the edelbrock manifold, have that honed out instead?

 

After price checking I fully agree don't waste your money on Extrude Hone! They want 379 dollars to do just the base, that's the exact price you can get the Accel base from Summit for. I never realized extrude honing was quite that expensive. You really have 2 options, buy an aftermarket base, or port yours yourself. The aftermarket base will cost around 400 dollars but you could also get one that will mate to Vortec heads and have a killer heads/intake combo right there. The other option is to spend the time porting your base yourself, it really depends on what you're willing to spend and what you want to gain.

 

Actually I thin kthe heads are a pretty bad restriction. I did the intake upgrade ...ported and simesed , added azz4 cam . Peak power is still under 5000 rpm ( 4900 peak) .... but the TPI wall was less harsh on the graph.

 

The length of the intake tract is still going to hurt the high end power, even if siamesed.

 

Holley Stealth Ram anyone? I know you live in Cali and it might not be feasible with emmisions laws but if you can do it it's the best performer and it's cheap compared to the others.

 

Actually there is a guy on here who opened his base up to 45mm. and siamesed the runners in as far as a dremil would go. He makes power all the way to 6000 rpm with TPI . It's my next mod to the intake

 

There's also someone on here who siamesed stock runners about halfway down and welded on some metal to make basically stock siamesed runners. I can't remember where that link was but I remember looking at it. Anyone good with a tig could probably do a similar mod.

 

At that point, it isn't even really "Tuned Port" anymore. I do not like siamesed bases a it messes up the overall air flow into the heads and can cause too much turbulance and pressure pockets..

 

get the edl. base (get it ported if posiable) and for the runner get the AS&M runners. you can keep the stock TB for now but port the peniulm.
a cam wouldnt be a bad thing ether. find a cam that will make power to about 5200 (with stock heads there is no need to go bigger)
that should be a nice setup.

 

Yeah but they are Tuned for the heads , and cam . You change any of that, the tuned effect is useless anyhow. Look at LT1 intakes. They are not tuned....does it matter ?

 

Look at an LT1 dyno graph vs. an L98. They both tell different stories as to the difference in intake tract length. I know this because I have owned both and dynod both. You can basically turn on of the dyno graphs over, hold them both to the light and the will almost match. LT1 and TPI operate in reverse ways. The LS1 works right in the middle.

The LT1 intake is a very short runner off the "air resevoir" or the main plenum. You siamese an L98 base and not the bottom of the runner, you are creating places for severe turbulance before the intake valve of the cylinder head which limits income air flow and will make your motor less powerful.

 

I was just refering to the fact that if the TPI becomes a non tuned runner. It doesn't matter. I know how runner length effects the powerband. The guy I said ported his base , did not siamese it ....just opened it up to 45 mm instead of the 42mm it came with. opening the top of the runners adds to top end performance. So Yes siameseing the top of the runners is a good thing .

 

I agree that siamesing the base without siamesed runners is a bad idea on the tuned port. Siamesing the plenum and runner entries is fine. For that matter I don't think you'de have much of a problem getting fully siamesed runners and siamesing the base, you're basically turning your long runner small plenum engine into a large plenum short runner engine. All in all the combo needs to be matched to your engine and for a 305 TPI I would stay with stock ported parts, with maybe a siamesed plenum and smoothed air foil entries until I went to change the cam, and do head work.

 

I wouldn;t siamese the base at all. Something was written about dual resonance point's or something like that( above me at this point )

 

what exactly is a 3 angle valve job and what does it do?

 

Where the valve seats to the head it takes it from 1 angle to 3 different angles so the air has a smoother transition. You should do a search on head porting and such, that's where ALOT of power can be made.

 

There was a GREAT article that I read on TPIs and it had extensive info on why NOT to siamese the base. I really don't remember the finer points, but long story short the turbulance of closing intake valve drastically effected the flow to the adjacent cylinder. The turbulance more than negated any flow gains.

That being said, the bone stock Accell base is easily capable of putting a car into the 11's with a super ram, if not a lot quicker. That's without porting. That REALLY makes me feel that siamesing the base isn't necessary.

I've also read several articles, and seen several back to back dyno charts that suggest a stock 48mm TB can flow enough to support ANY LONG TUBE TPI set-up you can make. Now I won't tell you I might not feel better with a 52mm, but you know, take it for what it's worth!!