I finally decided to go with the slp runners, but from what I've been reading, they don't work too well with a stock intake manifold.

What would work the best with the runners? And is there anything I would need to modify to also help gains?


edit: '90 350 with true dual exhaust

 

You could get an aftermarket manfold and it would work fine....but I dunno how well the ports from SLP runners and a monifold other than an SLP would match up. Personally, I'd siamese the stock intake, port the plenum, and of course match them up w/ the runners....aftermarket manifolds are just too expensive for my taste. I'm not sure how mechanically inclined you are, but there are tech articles if you want to take a look.

 

Thanks. Porting the plenum and siamesing the intake on my stock manifold looked a little too difficult for me. I have the time, but not the tools or experience to do it properly. So I think I'm gonna go with a aftermarket manifold. Now I just gotta figure out which one?

 

for the money you spend on new runners and a new base manifold, its not worth it. you may not even get a 10hp gain over the stock stuff. you will gain alot more usable hp and torque over the entire operating range if you siamese the stock base yourself. not to mention, your car will rev higher as a result. keep the stock runners, port the plenum, and siamese your base, and you will see more gains than an aftermarket manifold and runners

 

He said he doesn't have the tools/experience to port the plenum and intake. Remember, not EVERYONE can do things like that.

 

I'd choose between SLP, Edelbrock, and Accel. There's not gonna be much of a performance difference between the 3....so I'd just go w/ the cheapest one. But before you buy one, I'd do a search in the "aftermarket review" section, and see how people liked theirs.

 

i was just trying to explain he wont get what he is paying for. hell spend almost $700 for a tenth. porting the intake is not as hard as it sounds. alot of people are intimidated by it, but when i tried it, it was easy. you could buy a used base manifold for like $40 on ebay and practice on that til you get it right. but if he still wants to go the aftermarket route, more power to him

 

I have to just about completely disagree with you. More like most people don't even try it because it sounds too hard and they actually never even find out if they could do it. I mean there is absolutely nothing special about that kind of a porting job...... Just grind the metal off. That's it. Heck, there is even a tech article on it (follow the directions on the use of gear oil and you can do the entire thing with one carbide bit too). Measure how far you siamese the first pair, and match the rest to the same amount. If you feel really randy, you can even use a Sharpie to mark where the gaskets sit on each of the parts and match them all up to a specific gasket. But just saimeseing the base will yield the biggest gains.

Now the tool thing I can see...... But do you mean to say that you know absolutely NOBODY with a die grinder???? I mean somebody has to have one around you?

 

Some of us just can't bring ourselves to take the die grinder to $700 worth of new shiny parts. I know I couldn't. I bought an accel base and SLP runners. I port-matched the runners to the gaskets, and matched the plenum to the runners, but that was it. I couldn't bring myself to hog out my $500 base. It was already a perfect match for the gaskets, so I matched the runners to the same gaskets and called it a day. Maybe next time it's off I'll work up the sack to siamese the base, but I figured I'll practice on my old stock base first.

 

That is what I did. No sense in paying big bucks for a manifold you are gonna hack the crap out of anyways.

And my comments above are all aimed at those with stock bases... I can totally see how hard it is to put a $500 part under the knife right after you shelled out the $$$$ for it.

 

Well then I hope your Content to Be Slow


That Sort of mental block is the kind of thing that will always prevent you from rising above the crowd of "mee-too's"

So Do what you like

 

You have to realize that just cause someone owns a sports car, doesn't mean they know anything about cars. (not saying JD doesn't know anything) There's people that own cars like ours that dont even know how to check the oil....would you ask them to take a grinder to their parts?? Or even ask them to take everything apart to get to the manifold? NO. Yes, porting a plenum and intake is easy...if you understand the basic concept, but that is VERY intimidating to most people. And although the porting is easy....he also has to take apart the entire TPI setup, take off the manfold, put it all back together, and make sure the manifold seals correctly. Now can any joe shmo do all that? Just cause something is easy to most of us doesn't mean anybody can do it. If it's so easy....would you trust him to do yours?

 

Hardly. I'm just smart enough to realize that with my heads and cam, hogging out the baseplate isn't going to help a hell of a lot. I'm also doing a ton of mods at once, so I'd like to keep it relatively stock until I get the new computer/harness/PROM troubleshooting out of the way and tuned properly. Then I can hog out my stock base, throw it on there and see how it reacts. If I like it, then I'll hog out my accel base. It's a learning experience, and if you change 50 things at once you don't learn anything. And when you don't learn anything... you don't go faster.

 

Point taken, but those people are surely the minority on this site.

Sure....... with me watchin . But seriously, if you do a bit of research on it you can easily get enough information to do it even if you are a beginner. It's all about not being afraid to try something new and being willing to do the leg work to set yourself up for success.

 

You're right. If he, or anyone ever wants to go fast, they gotta learn how to do things like this. If I were him, i'd go buy a used one (i believe you're the one that mentioned that?) port that one, and if it turns out good, then get someone to put it on for them, but I'd watch/help as much as i could so that if i had to do it again, I'd know how.

 

ont he subject of porting the base and plenum and runners how long would it take?....i havent doen n e thing like this before and im also not intimadated or scared to try it i just would like to know the procedure and time im looking at...
i also cut out the pontiac emblem between the tail lenses on a 91 gta... and filled it with clear epoxy used transparent red spray paint and used two gm light sockets and spliced them in the lights so when i turn the lights on the pontiac would light up and during the day it would be bright red....it came out pretty freakin bad @ss

but were would i find directions or what not to siamese the base runners and plenum

 

Look at the main page of this site and click on technical articles and find the one on siamesing a TPI base. It has a very good description of it.

 

tahkn you matt

 

i read the article and it looks to me that the runners he siamesed were already siamesed he just took it farthur...and he really didnt give instructions just of what he did...

 

That's because he used SLP siamesed runners. They come as one cast runner for each pair of stock location runners with a divider in the big runner - a la the TPI base - that makes 8 individual runners out of the four. Some early model SLP runners even had them half fully siamesed and half divided..... But basically you just have to take the divider out of the runners a bit if you want to really siamese the pi$$ out of everything. But I am not sure if gutting the runners completely is even necessary once a nice siamesing of the base is accomplished........ Larger diameter runners and a part matching and smoothing of the new transition areas, yes, but fully siamesing the entire runner may not be all that worth while since the system will already have effectively cancelled out all of the negatives (well, a lot of them anyways) that the TPI LTR system has..... I would just smooth the transition areas - like where the runners meet the base now will just be a blunt surface without any work - and go from there.... Maybe siamese the plenum openings and smooth the transition on the inlet sids of the runners too...... But runner swaps and/or porting are easy and can be concentrated on once the base is off. Just match the base to a template of sorts that you can transfer to a runner to match to when/if the time comes.

Happy grindin

 

Siamesing an aftermarket intake opens up new worlds for tpi, such as the use of a huge set of heads. Everyone limits themselves to small runners. I'm running a set of 215 cc victor jr's on my 383 with everything siamesed and extrude honed. AS&M runners siamesed an additional inch and a half on the manifold side flow 280 cfm. Siamesed Edelbrock base flows 290 cfm. The victor jr's ported flow 290 at .600 lift, 260 at .400. The key is not settling for small heads ,rather, completely opening the induction system. Hence, the best of both worlds. LT1 RPM. TPI torque!

560 HP
540 lbs/ft

 

i have an electric dremel with 35,000 rpm's would this work? also what type of bit do i have to use....
on the plenum could i cut across it instead of leaving the "lip" between the runner ports so it looks like a rectangle with circular ends.....and how far "in" could u siamese the stock runners?
and when im done with the job how would i flush it out? i dont have an air compressor
thank you guys

 

Just Don't Go to Far down on the bottm Of the Divider.



Or this Will Happen.

 

A dremel will work, it just takes a lot longer. Try to get access to an air compressor. You can go at least 5 inches in on a stock manifold. with an aftermarket job you can go even further(more material). It really depends on the rpm's you want to run. The further you go, the faster you can spin it. Also, with an aftermarket manifold, you can get a more geometric shape(more conducive to proper airflow). The idea is to get as clear a line of sight as possible to the head port(eliminate the angles). You're definitely limited with a stock manifold, but gains are still there and it's a lot cheaper. Don't forget to siamese the runners and plenum as well. Especially where the runners meet the manifold. A lot of people fail to do this for some reason. In essence, your trying to create two distinct powerbands. Have fun!

 

With a stock heads and cam are you going to see much improvement By siamesing the manifold, plenum, and runners.

Im about to port my plenum (just waiting on gaskets)

The thing that scares me about the manifold is not taking it off the motor. Its removing the injectors. Or do you just leave them in and hope they don't get bumped.

Does anyone have flow numbers for a stock system like mine(check sig).

I have some experiance rebuilding a 350 years ago. But nothing with fuel injection and a computer.

Thanks

 

i have a base you can use to get started. there is nothing wrong with it and i will let you have it for 40 bucks plus shipping. im in the process of porting my 113 aluminum heads and really, there is nothing to it. just read up and try it. email me if you are interested in that base.

 

just one question. i am ignorant when it comes to some tools so i have to ask,,,i want to use a die grinder instead of a dremel cuz i read they're stronger and the porting job wont take as long. what is a good brand i can buy at the local home depot or lowes?? i dont want anything fancy, just somethin that will do the job and will last. i'm definitely trying this before i shell out money for a new base. my plenun and runners are already siamesed.

thanks

 

it's best to remove 'em. just disconnect the fuel lines, loosen the 4 bolts holding the rail to the base, and slowly pry the rail up. the hardest part of this job for me is getting the back part of the base to seal right.

 

i got my die grinder from summit racing and it performs execellent! the best part is, it only cost 35 bucks and it comes as a kit with some stones. it has a 1/4 inch chuck. that is what you want to port intakes and heads. if you need cutting stones to make the job faster, they also sell those in packs of three. i bought the non ferous cutters for cutting aluminum for 65 bucks. im almost done with both heads and they still cut very well. so for 100 bucks you can have a very good porting setup. good luck!

 

Dremel tool's are crap!!! You go through bit's like they are made of butter. If you can't get access to a compres. a die grinder is the only way to go!!