porting plenum and runners.
 

alright im going to try and attempt to port my plenum and runners an the base. are there any tutorials on how to do this? how would i gasket match them? and should i siameeze the plenum and base? also what kind of a tool would i use to do the porting?

porting your runners wont really help you out at all as air will still be restricted in the middle of the runners.

I got Edelbrock runners and had them ported. Definitly get some aftermarket runners.:nod:

they prob wont make more power stock, but as you go along with other mods such as headers, catback, tuning ect, edel, slp runners ect port matched with ur plenum will make for some decent upper end and kickass midrange.

woah woah woah, back up the train here guys. We need to make sure he gets things in the proper order here first. Everyone on here will tell you to do headers and exhaust first. Then install a cam in that peanut cammed LB9. When you do the cam simply port match your stock intake components and remove the EGR walls in the inlet of the plenum. Stock TPI intakes will flow 195-205cfm per port, a good bit more than the stock heads will flow. So anything more than a cheap easy port match is a waste of time in my opinion. There are many people on here running mid to low 13s at 100-103mph on the stock intake parts. Spend your money on exhaust, then a cam, then heads. those are the first 3 bottlenecks before the TPI. Anyone else agree?

well usually when they suggest porting plenum and stuff like that, they're looking for 'bolt on' type deals, most people don't have the knowledge to install heads or cam. Not that im saying that he doesn't but im sure most people start with bolt ons and go from there.

ya i just heard that the tpi system was pretty bad on the flow charts i dont want to install a cam or heads at the moment. but i figured this would be an easy thing to do if it would help at all. so you dont think it will help at all with stock components?

Well its not like it will hurt anything.You may see a little better throttle response, but I dont think you will see much hp gains. I agree with the aftermarket runners though. They have alot more material than the stock ones. I just got some SLP Runners that im gonna do this to,but a few other mods to go along with it.

Yep that's the order I would do it if I had to do it all over again.

maroon88iroc, It will not hurt anything to port your stock components. You may see a sight gain, you may not notice much. If you want to port your stock components, the go right ahead, enjoy the project, you wont hurt anything by doing it. I just dont want to see you spend a ton of money on aftermarket runners and base when you will see a very minimal gain if any. I think everyone here that has posted would agree with that. Hope we've helped!:)

yes you have helped and thanks for the responses. i already have full exhaust and a hypertech chip. im going to do the ram air mod and then the throttle body bypass. im wanting to change over to a t-5 but idk about that right now. what mod would you suggest i do next?

Grinding down the ERG wall in the plenum, ram air, K&Ns, and an AFPR will definitely help. I definitely would not siamese the base. About all I would do to your base intake would be smooth the casting and grind down the lip at the runner entrance,,, but I personally wouldn't think it would be worth the hassle of pulling the intake. Wait to do that when you get a set of heads that you'll need to grind on the intake.

See my comments again in post #5 directly above, that should answer your question.

No. You will find lots of disagreement. We don't want to know what is going to make a real, substantial difference. We only want to know what is going to be EASIEST, and seem like it should make a difference - Like bolting on a 58mm TB, hacking the screens out of the MAF, installing a designer air filter and CAI, bolting on runners, and clipping an airfoil in the TB. No one really wants to know what actually WORKS! That might involve some labor and a little planning. We'd rather spend $2,500 on bolt on parts that should make us go faster, then post hundreds of questions over our ten-page signatures asking what other members with "all the bolt-ons" are doing for times with a 0.385" lift cam, 85# valve springs, heads with more constriction than a quintuple-bypass patient, and core-shifted factory iron exhausts funneled into 2" pipes.

No. We don't want to know...

I agree with Vader. And read the stickies at the beginning of the forums. This dead horse has been beaten for the last 20 years. Hopefully they'll get a search function working soon for newbies like you.

If you're really set on plenum porting anf matching the runner openings (which can be pretty bad as cast) you can follow this guide:

Plenum Porting.pdf

Just don't expect any significant gains (or even noticable ones) from this process.

where can i get an afpr from for a tpi?

HI maroon, you can get them at many differnt places, like summit, you should make a trip to the new one up the road from you its a nice facility, I personally like the holley unit because you can adjust it with your fingers and do not have to have a wrench. But it want do you any good unless you get a fuel pressure gauge to hook into your fuel rail so get one of those also, start off with about 46/48 lbs should be fine for the street. GOOD LUCK.

thanks man and ya ive been up there it is a really nice place. i will check around about the afpr. how much do you think it will help? isnt the stock fuel pressure set at 44 lbs? what would you suggest running it at at the track instead of street.

I run mine at 48lb all the time that works great on my 5.7 and the difference between 48 and 50lb is just a little but much harder on the injectors, 48 seems to be the best you get a better spray pattern also, that is one of the best quick mods I have made and it is well worth it, its something you can actually feel in the seat of the pants. I think some dyno work has been done and it added like 12/14 hp but like 30fp of torque, on a 5.7 so it does make a big difference, I think its well worth it....

i looked at summit and they dont make any gauges that are 2 1/16 to fit my gauge pod. i dont want to buy autometer b/c they're like $200. i guess ill have to look on ebay.

should i just make my own afpr using the tech article? has anyone else done this and what were your results?

Just get the holley one, you will be much better off, also the gauge I was talking about is just a temp, you attach it to the schrader valve on the fuel rail. You can leave it there but it says it is for temp only. I think eventually the heat gets it and causes the face/lens to deteriorate. But once you set it, I have never had it change, so it stays pretty much constant.

I converted my FPR to an adjustable, and documented it. If you use this design:

TPI AFPR Conversion.pdf

Be sure to use the disc instead of the ball. Many people have had difficulty sizing the ball correctly, and it's just easier using the disc.

FWIW, after all the tuning and programming, my pressure is right about back at stock settings for best overall performance.

vader that link doesnt work.

Cool
 

Glad to hear of another Iroc being modded. I have been going through the same process with my 88 5.7 Iroc,,,it is identical looking to yours. (here is a pic) I have been trying to document my changes with real track time to varify what everything was worth. I started with a bone stock 50,000 mile Iroc and ran 14.60's at 94 mph,,,I installed 1.6 rockers, Hooker headers and Y-pipe, and then an Edelbrock cat back exhaust system, and removed the cat at the same time. Also an adjustable fuel pressure regulator (I went with the holley for ease of adjustability) I have now ran a best of 13.92 at 99 mph,,,I have not touched the intake system yet and I am doing this on stock rubber and the original 2.77 gears. I have been running 48 lbs. on the street and baselined the car with that and ran 14.10 at 98 mph,,,,with a simple bump in fuel pressure to 50 lbs. I ran 13.92 at 99 mph,,,so fuel pressure was worth alot with my car,,,but I agree with Vador,,,,Fuel curve should be tuned with the chip and pressure returned back to a stock setting of 44 lbs. That is what I plan to do as this is the correct way to go about it. The adjustable regulator was simply a quick fix for my car as I feared it would run lean with all the exhaust mods.
My next mods will be the intake system, I am going for aftermarket runners and porting the upper plenum at the same time, I will then run the car again to document any improvements, then some gears, converter, tires, and in the end I plan on computer tuning as well since I am still running the stock chip. I should have an entire book on this thing to post here when I am done. Unfortunately it's been a long process as winter time shuts the tracks down here for several months. Goodluck with the mods,,,every little bit adds up,,,,Larry.
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Well shucks,,,it won't let the picture come through since I posted it in my other thread called,,,,My nearly stock Iroc broke into the 13's,,, Damn computers,,,,:lmao: Larry.