okay, is it possible to port my stock intake manifold? I am trying to keep costs down half way decent, but I'm afraid that the manifold will be a bad bottleneck. I'm putting this TPI on a crate 350, about 300hp, SD conversion, gonna port the plenum and all, and was gonna get some runners from Ray Royer on here, but he won't return any of my e-mails or anything, so I guess that is out. Also, I am going to keep the stock exhaust manifolds and all, and keep the stock exhaust off of the '86 Caprice I am putting all this in, except maybe gut the cat or something. I know this will hurt my performance a lot, but by how much? I don't want raw power or anything, just looking to about double the power over what it is making now, and to gain a few mpg in the process (shooting for 22mpg).

Thanks in advance. You guys are great:hail:


oh, almost forgot. Can anybody give me a site where it gives all as to what you need for the SD converion besides the harness BS? I know you need the MAP sensor and all, but I don't even know where it goes, or if I need some other pieces or what. BTW, I'm getting the S&P harness, so wiring will be taken care of.

 

You are choking the crate motor with stock exhaust manifolds and catback. Crates are rated with headers. The ported TPI base will flow better than the stock TPI base, but not great. You might see 240 RWHP after all the restricition.

 

With what you’re planning to build, you shouldn’t worry about the “TPI bottle neck”. In my opinion (for what it’s worth) a ported stock TPI base (done right) can more than make up the loss in peak HP with an increase of torque on milder combinations - compared to carbs or single plane EFI systems. On the crate engine you have,,, you can pretty much keep to the stock contour of the base and just port everything a little larger than cast. You’ll want to grind the entire port length which means you’ll need a 6” shank burr,, or if you’ve got a ton of time on your hands, it can be done with a dremel and flex “wand” attachment. Best runner bang for the buck are the SLPs. Mildly cleaned up SLPs and porting the plenum along with matching it to the opening of the SLPs should be adequate for your combination. Taking an additional inch or so from the TOP of the dividers of the SLP runners should give you a small increase of HP and RPM while retaining plenty of torque that you’re going to need for the 86 Caprice.

I’d definitely recommend a set of long tube 1 5/8” headers for the Caprice. They’re cheap horsepower (and torque). A dual 2.5” exhaust and “X-pipe” would do wonders also,,, and this is one of the few areas that you can increase power AND gas mileage. However, I understand the budget build and if you’re going to stay with the cast iron manifolds (for now anyway), take a grinder to them, making sure their port opening is larger than the port on the heads, open them up, and smooth out the entire casting. I’ve ported cast iron manifolds before for myself and close friends,,, but it’s usually cost prohibitive for me to do it for others. You can get decent results from porting them though,,, I ported a set of cast iron manifolds for a basically stock 350 TPI that ran 13.40s w/o cats through the stock exhaust system. He later switched to shorty headers and picked up less than .1 seconds. So,,,, if you have more time than money,,, knock yourself out and go to town on them.

Good luck on the build!

 

okay, what if I get those 1 5/8" headers, but keep the stock exhaust? Would that do anything? I can find a nice set of used headers pretty cheap around here, but I really don't want to go to a dual exhaust or somethin. Really want it to be a sleeper (the excuse I like to tell people), and I don't want to attract any more attention than a 16 yr. old usually does (real reason).


But your saying to get a 6" shank burr? That just goes on the end of a dremel, right? Cool. Okay, so do that to the intake manifold, get a set of SLP runners (would rather get the nice set of Accell ones from Ray Royer, but he won't return my e-mails or anything) and port those, plus siamese the top 1", port match the plenum, and that should be good? Cool.

 

A set of long tube headers will do OK with a y-pipe into a single 3” exhaust. It will definitely be much better than the stock manifolds, even ported and running through the rest of the stock exhaust system.

6” shank burr is for a grinder,,, air or electric. If you have a dremel, you need the flexible “wand” attachment to go the entire port length,,, I think it’s around $20 or so – it’s going to take you a long time to port the intake with a dremel though. It’s slow go,, but if you haven’t done a lot of porting that might not be a bad thing. Follow the port shape,,, making it a little larger all the way around – no need to hog it out for your application. Also,, stop frequently to check your work,,,, and put the same amount of work into each port. Don’t go over board on the first intake port. In fact,,, I’d recommend you do a mild clean up all the way through on the first intake port,, then repeat that for the remaining seven. This will give you an idea of the time involved and whether or not you have the time to actually “port” the intake with a dremel.

The Accels would do better than the SLPs right out of the box,,, but if you don’t mind cleaning the SLPs up, and buying a set of the 1.75” runner gaskets (Mr Gasket has a set that’s like $16),, the SLP’s will do just fine. The SLPs come with stock gaskets that hang into the ports,,, which is not good and could be why some don’t see much if any gain from bolting them on “out of the box”.

 

http://www.american-carbide.com/Burs...ection=4&Cat=2
found that when I did a google. Yea, that is what I was talking about. I have a bunch of air die grinders around here that have blades like that, I just need to get one that is 6". Also, what do I need to port the plenum? Same thing? Can't I only port the plenum like 1/3 the way in from each end? Also, which burr do you think would work best from that link I posted? I think that Ball Nose one will be pretty good IMHO.

 

THANKS FOR INFO

 

whoa, get your own thread there, buddy.
My guess, 330rwhp.

 

If you want to run headers into stock crush bent exhaust sytem, straight pipe the cat and run a cutout before the muffler. It should be an alright compensation for lack of a good mandrel bend catback. If not a cutout, at least invest in a muffler that you can "uncap". Crush bent exhaust sucks and it'd pay off to help it out in anyway possible.

 

yea, I just joined a Caprice forum and started asking questions about exhausts.

 

I love budget builds. This is certainly... budget. Let us know what you decide to do, it's interesting.

 

Well, I HAVE to get a S&P complete wiring harness, a nice set of runners, new injectors, all the PROM burning stuff, and I had to get the brand new 350 crate motor and a very nice and built up TH700 (got both from a good friend for $500). I'm just tryin to keep costs down without really cutting corners. BTW, I'm only 16, and i have to work to get all these mods. My parents haven't put up a penny for me (besides getting an alarm for me behind my back for Xmas), and I have had to pay for my car and the mods, sterio, interior, etc.

So, its gonna be kind of a budget build, but its gonna be nice in a year. I would say when it is "done", but will you guys back me up in that its never fast enough and never "done"