Thanks for the tip 355! I'll give that a try

 

Great job! Really nice to hear the end results, especially you stating you could feel a big seat of the pants difference. I knew it was going to be a bad idea to look at this thread! I've been staring at a TPI setup in my garage, and now I want to go through and port it. I won't even say what for because everyone here will tell me I am dumb for thinking it.

 

Thanks Fast I will also, I know my timing we set just above stock @ 8'

 

Thanks, and I won't ask! If you have the system there I would go through it. It is not too much work and it is a little fun making your own performance parts, and getting to feel the results of your work.

 

Yep, thinking I might just go through it for fun. Being a former die maker, handling a grinder to do this is second nature for me. And it might be easier to sell being ported, if I dont use it. Seems like every time I mention putting this on the 400 in my '79 K20, people rag on me and tell me the TPI will never feed it, the engine is too big. TPI can't feed a STOCK 400?! Give me a break. Porting would definitely help it though. Now to keep an eye out for runners...

 

I have actually tuned a TPI 400. It had TBI 350 heads and a Comp 260 HE cam. Was in a G-van based class C motorhome. Was not a high RPM engine by any means but pulled strong right up to the 4,500 rpm upshifts provided by the stock TH400. The 64cc chambers brought it up to 9.0:1 compression. It ran all day long pulling the 10K motorhome and a 4,000 lbs boat on 87 **** gas.

 

Yes, you get it! That setup would go perfect in my truck. TPI 400, TH400, 3.73's and 31" tires. I don't need power above 4500 rpm, not the way it gets used and driven these days. I have maybe taken it above 4000 rpm a handful of times in the time I have owned it. It is set up to have a slide-in camper in the bed if needed, and pull a trailer. But in all truthfulness, its just a cruiser that works occasionally. I don't want to highjack the OP's thread, but the more I think about this the more I want to do it.

 

Just do it! No worries on hijacking this thread, it has become more of a knowledge sharing at this point... which kinda is the point!
I actually feel if you do this on you 400 truck engine you might feel pull up past 4500 now. At least that what it did for me. Arizona Speed and Marine still makes the oversize runners like I pictured in the beginning of the thread. Look them up and call them, they make these to order and I don't believe they stock them. They are a little over $500 shipped with gaskets and the 4 bolts. You have to use their gaskets and the bolts provided, don't try to cut originals to fit and the 4 lower center bolts need a different length to work. Some have made spacers on the lower centers to utilize the factory bolts.

 

What do you guys have for exhaust? I still have the factory L03 exhaust. This is the "Low Output" 3 system with under 2" outlet manifolds, that great flowing "T" pipe, and a whopping 2.25" primary pipe. It may have an aftermarket muffler as it sounds really droned and I can see where it was welded in. Someone could have changed the FP at some point so they may have had to cut the muffler out. This has to really be choking me down especially after the breathing intake. I am also wondering if this has something to do with the hesitation. My car is in the shop so I have not tried the trick Fast 355 suggested.
It is in the shop for this, complete new system from the heads back. These are the L69 performance manifolds, 2,25" outlets. Next is a Magna flow 16450 Y-pipe, 2.25" primary pipes into a 3" pipe. I will have a 3" test tube made by the shop to take the space of the Cat. Next is a 3" Hooker Super Competition cat back system with the Aero Chamber muffler. 2.5" dual tail pipes with modern looking dual outlet polished stainless tips.



As stated in my original post I am trying to stay with the stock look on the engine so that is the reason for using manifolds. I also stated I would be OK with leaving a few ponies on the table because of this. I also said I would go through the exhaust but at the time of the post I was not sure what that would look like...well now I know!

 

Hey Vinny, when you get a chance go over to Paul at prime tune and have them check that your TPS voltage to be about 0.5-0.6 volts at closed throttle as Fast355 suggested. Mine was around .45 V and bringing it into spec range really improved drivability.

 

90-92 tps spec is .67-76 and is self zeroing.

 

I forget the 90-92 was spec'd higher and from what I remember non-adjustable.

My response was specifically to the MAF TPI I responded to.

My TPI was an earlier system with an adjustable TPS. I had the TPS Voltage set to the higher end of the TBI spec to match the 95 TBI PCM I was running it with.

 

That should make a very noticeable power and sound difference.

In 1990 the only difference between the 210 and 230 HP LB9 was the manifolds and Y-pipe. The 210 HP version had the L03 manifolds and single cat Y-pipe. The 230 HP version had the larger HO manifolds and dual cats. The gain was substantial across most of the power band, 15 ft/lbs of torque at peak torque of only 3,200 rpm even.

My educated guess is that you will see gains of approximately 30 hp from that system compared to the L03 garbage.

I would consider some stronger valve springs and 1.6:1 full roller rockers for the next mod to take advantage of the added airflow potential and keep the valve train safe to redline.

 

Thanks Guys. I did notice the last TPS I installed really did not have much of an oblong hole for adjusting. The other thing I noticed after I set the IAC that if I did move the TPS a ltlle amount, it did seem not change anything.
.

 

I think you are right fast355, i tend to agree with you and once I found that I had the better cam well those HP numbers don't lie! I am also hoping the pull will go to over 5K now with this system. I went by the shop to check the progress and saw my LO3 system sitting there in a pile looking exactly as described...GARBAGE. There was nothing worth saving down to my broken chambered "intesity"? cheap a$$ off brand muffler.

I should be getting it back this afternoon as when I went by they had the manifolds and y pipe installed and was working on the rest of the system install. The MF Y-pipe fit perfect. I think this may just help that hesitation as I can really see where I was having trouble getting those gasses out.

I have been already looking into the roller rockers fast, but not springs. What rate springs would you recommend I use?

 

I have had good luck with many of the kits that Competition Products sells. Just grab the shim kit to eliminate the valve rotators if your heads still have them. The kit I listed below should have no issue controlling the mild stock roller cam clear through 6,000 rpm. Especially if you shim them slightly and get the pressure at the installed height up to about 125 lbs on the seat.

https://www.competitionproducts.com/.../#.XbhzHppKiUk

 

Thanks Fast! for $60 I think I will order these up next week and start gathering the parts for this next mod! Thanks again for the idea. I like that I will be able to get 6K with these.

What do you think of these for the rockers. https://www.summitracing.com/parts/cca-1418-16

 

Personally I would not use them. Most of the friction reduction of roller rockers come from the roller bearing in the fulcrum not the tips. I have used two sets of Jegs brand narrow body self aligning full roller rockers. They fit under the stock center bolt valve covers.

https://www.jegs.com/i/JEGS/555/20145/10002/-1

On another note, have you gotten the car back? How is it running with the new exhaust?

 

Good job vinny! Like seeing what can be done with some DIY and stock parts. Know what ya mean about getting to the last few holes and wondering why you ever started lol
Keep it up

 

I do not believe your powerband will carry much above 5,500 rpm but your valve train will be stable until 6,000 rpm. It is important that it stays stable until higher than the RPM you run at since the springs will lose pressure as they age.

 

nice work

 

Still wondering how you like the upgrade Vinny?

 

I drove it the 10 miles home from the shop last week in rush hr. traffic. I really did not get a chance to truly test it out. Busy week last week I wanted to put some miles on this past weekend but it rained all day on Sun. I want to wait until I get some good miles before I give my assessment. I could tell a difference in that short time but never really got on it like I want.

 

Very nice work Vinny

 

I think I’m going to try this this winter. Doesn’t seem too difficult.

 

I was able to put some miles on the car the past few days. I am impressed! First the thing sounds awesome now. It has a much meaner sound to it especially under load. More air in and more air out and you can hear it! The performance difference is seat of your pants especially when it is pulling through the gears. It does pull through the gears now and when you give it throttle it really has some power behind it. The power has definitely shifted to a higher RPM but you can really feel the difference from that choking L03 system. Until I did this entire exhaust I really did not realize how much that system was holding this engine back. I think this system has now added at least 20 hp, and maybe FAST is right and it is more like 30. The hesitation is still there but I will say that once she heats up to 160 it's all but gone. I like the performance of this system but I will say that I also like the sound and I was not to sure about that. I am honestly very happy with the choice I made for this system, from the manifolds to the quad tips, this 5.0 has responded well!


Gonna concentrate on trying to get the tune next. I need to get that sorted.

 

nice growl, but not too loud, congrats!

 

Thanks Jim, and my sentiments exactly on the sound.

A couple more observations now that the exhaust is complete. When sitting at idle you can really hear the air getting sucked into the engine now. I did not notice this from just the intake mod, at least not with the hood closed and me standing 10' from the car. I have the Spectre filters and my Air Box is cut bottomless. When cruising 35-45 in 4th gear and I give her some throttle it will actually accelerate in the high gear now. This was not the case before the exhaust mod. It did do better in this RPM/gear range after the intake but that coupled with the exhaust it has totally taken any of the "blah" feeling we all know with this 4 speed auto 305 combo. You accelerate and she responds with zero hesitation. Overall driveability is just flat out awesome!!! Let me be clear, my hesitation is only from off idle transition and as I mentioned goes away after a little engine heat. In any gear if you give her gas she just flat out responds. I can pass with ease now regardless of gear.She down shifts quicker and gets to the power band quicker. Sooo much smoother through the gears and all of this was there with the intake mod it just has been enhanced 2 fold now. I was cruising around 40 yesterday on a 2 lane road, pulled to the left and gave her some throttle, she smoothly shifted down into 3rd, RPMs cane up to 3K or so, the exhaust opened up and next thing I know I was doing 60 passing the car on the right! I could not be happier with the car right now.

Some totals, Complete Intake breathe mod cost me $1300. Complete Exhaust cost me $750. So for right about 2k (no labor included) you could get what I hope to be about a 70HP increase.

 

Knock-Knock? anyone still out there?

 

I am finally getting my tune...yeah! I finally got Tuner Pro RT to work. It was my old laptop that was the problem. I got a new windows 10 laptop, Loaded Tuner Pro RT. I bought a Moates Extreme ALDL cable with the 10K switch. I did the pre settings in Tuner Pro, just looked at a couple youtube vids to make sure the right boxes where checked. Plugged in the cable and windows 10 downloaded the drivers for it. Went to the acquisition box in tuner pro, did the cable check and all was good. I went through a lot of troubles before with this and turns out I just needed a new computer. Now I just plug everything up, cable to the car and the computer, start up tuner pro, turn on the car and hit initiate in TP and she instantly connects and stays connected when driving. No witchcraft involved! I have not figured out how to make the custom dashboard but I must say it is pretty cool seeing the data list in real time. This was my initial run with the aftermarket hyperteck chip.

 

I am working with Brian @ Tuned Performance for writing my bin file for the chip burning. He rented me a chip burner and I purchased 2 chips and he sends me the bin file over the internet and I program the chip. This is working great as we don't ship back and forth.

He sent 2 files, and I have the stock chip plus the Hyperteck. I will say that the tune is a must when doing a mod like this I you REALLY can feel, hear and smell the difference between chips. The hypertek chip was actually hurting me as it was too rich and that I believe was the cause of the hesitation. I put the stock chip back in and the hesitation was gone, but the car really fell flat in the upper RPM. My exhaust sounded different when switching the chip. Next I ran the Chip 1 and it was much better than stock, and more refined than the HT. Still some hesitation with this tune and a little slow on throttle response but good pull at the top end. Finally chip 2. This one worked the best, no more hesitation and rich smell. The car starts up quick. The exhaust sounds "cleaner" and with the HT chip there was a weird exhaust note coming from the Y-pipe, almost sounded like a leak. The off idle transition is now smooth and so is the mid range acceleration. It may suffer slightly @ WOT. Brian has refined chip 2 for smoother fueling which I will burn that bin and try it later today. After trying the 4 chips I will reiterate and say that this is a MUST when changing anything that has to do with fuel/air ratios. I thought the car ran good on the HT chip and I was mistaken!
I will post up my info from chip 3 but from what Brian said chip 2 looked good on the data end, one thing I noticed in looking at the list data in TP when I got back from the run was my BLM and INT where right on the money @ 128 with chip 2

 

Ooooh. The fun continues!! Love this thread. Chip burner? I'm jealous!! There's nothing like the right tune.

 

I knew I shouldn't have come back to this thread...

 

Yeah Tootie, what a difference the right tune made. #2 ended up doing the trick. We refined #2, Brian said it was "spiked" so he smoothed it out. The computer numbers looked good but the car did not like it. It did not run as good as the "spiked" tune. The burner is the way to go, it made the process sooo much easier. I also had ZIF sockets Brian loaned me, basically a quick release for the chip, lift a lever and remove and install the chip. Brian would e-mail me a BIN, I would burn the new file, install the chip, do a dta run and send him back the recorded XDF and he would make the adjustment and e-mail the new BIN. If you are keeping the TPI on your 350 build you may want to see if your tuner will work this way, I know you went through 7 or so tunes the 1st time. It was pretty easy or as easy as this system could be. I did not take a pick of the data list but all the numbers seemed to be right on. Both the BLM and the INT were right on 128.

The car runs and performs like it should. Hesitation is completely gone and the throttle is smooth through acceleration. Starts up quick at all engine temps. It pulls through all rpms and seems to go to 5500 before it falls off. Exhaust comes to life @ about 3500 and has a reel seat of your pants kick when the trans downshifts and the revs go up. Did lose a little of that low end "grunt" but the gains in the rest of the RPMs are well worth the trade off. Has not lost a thing in the burnout dept, in fact I can roast the tires for a longer distance now .

I feel the tune is a must when you are doing this mod. When I ran on the stock chip I really did not feel all the extra power @ the higher rpms. kinda like it was chocking it out or running it lean. The HT tune was rich and was not smooth or driveable until you hit about 4K. I feel that all this work was well worth the time and $$ as the outcome is awesome. This made a HUGE difference in my car, it was always fun to drive but now it is a BLAST to drive and now I can hang with those performance mini vans and hopefully outrun those Ford Fiesta performance cars!

If you are still following this Brian I just want to give you a big for all you did to get me tuned up!

 

Hey Vinny , thanks for the shout out. Glad it only took two tries to get your tune right.
it can take multiple tunes sometimes and with tpi maf for example there are some bugs with the maf tables and sometimes you end up with corrupt tunes.
having a burner on hand is way easier than shipping chips.
glad your runner upgrade and porting job was such a success.
now if we can get your buddies car tunes your have to do another race

 

I recently ported out my plenum for a similar project on my L98 GTA and this thread was a huge help with a lot of great information and pictures.

 

Used Plenum and Intake from what vehicle years and CID? 88-92? 305/350?

 

Be sure to get the right parts, if your car is a 90’ you have a MAP sensor/speed density instead of the 85-88 and 89s MAF style-so be sure to get a 90-92 plenum and it does not matter if it was off a 305 or 350(they are identical). Easy way to spot the plenums is the lines on top change length for different styles. eBay usually has a few on there for sale.

The intakes are very similar too but be sure to get an 87’ and up F body one if you want a stock one because they changed the bolt hole patterns in 87’. If you find a aftermarket intake they have provisions for both styles of bolt patterns and EGR differences between F body and Corvette. This thread of Vinny’s has a lot of great info.

https://www.thirdgen.org/forums/hist...fferences.html

 

Yes, mine is a 1990. So i could buy new Runner's for a 350, find a 90-92 Plenum from a 350, find an 87-92 Manifold from a 350 and they will bolt up to my 305 TPI? I'm trying to read and take in all the info to make sure it's correct so excuse my questions if this has been covered before....so many threads with similar info. Plus i assume i could get 22lb injectors then reprogram the ECM? or stick with 19lb?

 

I would stick with the 19lb for this mod. If you changed the heads and cam then you would benefit from the larger injectors.
As Reddragon stated there is no difference in the 350 and 305 parts, it is the model years you should be focused on. You can modify the earlier year parts but it is much better to just find the ones the work with the later Speed Density (MAP) system. This includes the runners, the later models did not have the 9th injector so the runners should have a block off plate.

 

Hey Vinny I know this is a old tread but I have a accel base and already ported a plenum. Looking to get some highflow slp runners. Do you still think it was worth the money for the AS&M runners. Thanks

 

Wow, I got an e-mail that you responded to my thread, after all these years!

Yes I do. The runners are the choke point for all this and if you connect up the larger opening plenum and base to stock runners it might really work to a disadvantage. I just looked and they are $575 @ AS&M which is only about $50 more than what I paid 5 years ago. You can check the for sale section here and Ebay and you might find a used pair and save some $$.

BTW 5-6 yrs later my car still performs as good as it did when I did this mod so still feel all was worth it.

 

Ok cool thanks. I am going with some used slp runners. I talked to brian van schoiack he said the AS&M runners weren't as good now some vacuum issues. Will definitely be working with him on a new tune. Thanks again for replying back.

 

Yeah Brian is spot on. I had a heck of a time with my AS&M runners getting them sealed up. Now a contributor was the ported intake. I would encourage anyone before startup to do a "smoke" test. It can be as simple as a Harbor Freight hand pump and a cigar. Plug it into a vac port on the back of the plenum and take a latex glove over the throttle body. One can quickly see how good the thing is sealed up. One can find a video on You Tube.

 

It’s a great idea to smoke check after any tpi runner removed or different runners. Normal to see some leak on throttle shaft even new aftermarket leak alittle.

 

Make sure you use the proper sequence when tightening the runners. Start with the center bolts on the lower runners and work out. Then tighten the plenum bolts from the center out. Do not tighten the plenum first, you will never get the base to seal properly.

I did not know the new AS&M runners had issues now.