TPI and 383 questions...

[bigblaza]

Ok, so I just got a TPI setup off of ebay for pretty cheap. It came with everything (TB,stock runners, plenum, injectors, MAF, base, and uncut wiring harness w/ ECU). From my limited understanding of TPI is that it is great for low end torque and low-mid HP as long as you are below 4200(ish) rpm and after that it runs outta steam.
I've been to thirdgen already and they hate any questions that have anything to do with trucks and I couldn't find out exactly what I needed.

So my questions are: Will I ever need to go above 4200 rpm (dont have a tach)?

I mean has anyone either done this conversion and found that they could use more HP up top?

I've read that you can throw in a stealthram, superram, mini ram (ect) to get better performance at higher rpm, but comes at expense of low end torque, but how significant of a loss? would it be worth looking into for a semi-off road/daily driver/fun truck?

What about running SLP runners and doing some port work?

Maybe a better intake??

Im basically just looking for a solid setup. All I have right now is a stock (1987 5.7L) TPI setup and a bored .030 block. Any help would be appreciated...

 

[dyeager535]

For the cost, the alternatives are very prohibitive. You can look at the intake, then you have to look at fuel rails. Which are PRICEY. I would suspect, at least new, that a stealthram would cost somewhere around $1000 to put on a motor. Probably not including a larger throttle body.

Unless you mud run, or have a horribly geared setup (31's w/4.56 for instance) and like to go fast, you probably won't hit 4200RPM very often, especially not in a situation where winding it higher will help.

Since you already have the parts, throw it in as-is, and see how you like it. You will definitely need injectors and to modify the PROM, those are givens. Don't know what injector size for a 383 is recommended, but I can suggest Ford injectors from Summit. They are referenced on thirdgen a bunch. Cheap for what you get. It's what I'm running.

If you find the setup is too restrictive for your use, you can always get the stuff later...it's not like in your case you are going to have to go get the stock base, THEN upgrade, you've already got it. I would stay away from trying to get things to work with the stock TPI runners/base/TB/plenum, as they are just a huge hindrance. When you start looking at the cost for SLP runners for instance, you've still got every other piece as a restriction....which means more mods, which means you might as well have gone with a completely different setup.

I *think* the LT1 intake is supposed to be an upgrade, but I don't know much about it.

My truck has plenty of power, but I feel it runs out of steam down low. Could be cam, could be the TPI setup itself...but since I don't HAVE to run it that high, I'm not worried about it. I think a bit healthier cam wouldn't have hurt low end enough to matter, while increasing top end enough to notice.

 

[bigblaza]

No, I have 39's" with a 4.88rear. I "think" thats ok (could be wrong). I was just hoping to get all my info and research done before I build. I dont want have everything on there and then find out I could have done 'this' or 'that'. I also want to be able to get the most out of the 383 without sacraficing and uneccassaries (ie: throwing a HSR and getting more hp in an rpm range that I will never see, at the expense of low-end tq that I will definetly use more)

like I said just tryin to get my facts straight before I start...

 

[dyeager535]

Check for some of the 383 builds over on thirdgen. I think you are on track with the TPI unit simply being too much of a restriction to make as much power as it's capable of.

I wouldn't doubt that with the right heads and exhaust, you could make as much, if not more low end with the 383 and say a stealthram (and I know there are others out there, that one just comes to mind quick, no endorsement) than you can with the stock runner setup.

As long as you keep port velocity up, you'll have plenty of response and low end power.

 

[4X4HIGH]

My last blazer i had a 383 with TPI (MAP system 90-92) running 24 lb/hr injectors with a 1050cfm BBK throttle body and could pull hard RPM's up to 6500 all day long. The stock throttle body is what limited the RPM range. I know this as a fact since i started with the stock TB then went to the larger BBK TB.

 

[bigblaza]

My last blazer i had a 383 with TPI (MAP system 90-92) running 24 lb/hr injectors with a 1050cfm BBK throttle body and could pull hard RPM's up to 6500 all day long. The stock throttle body is what limited the RPM range. I know this as a fact since i started with the stock TB then went to the larger BBK TB.

So after putting that aftermarket TB in did you notice any loss in bottom end tq? Are you recommending the bbk 58mm(right?) for a build? What about MAP??

 

[4X4HIGH]

So after putting that aftermarket TB in did you notice any loss in bottom end tq? Are you recommending the bbk 58mm(right?) for a build? What about MAP??

In my case there was no loss but rather a gain. I can't say if you would benefit from it or not, it would all depend on the specifics of your engine. In my case it was night and day difference all across the board. My engine was a full roller though so that might have had something to do with being able to achieve higher RPM's as well.

 

[bigblaza]

Well like I had said before, I only have a bare block and a stock TPI setup. Thats it. I am open to any and all ideas for this setup, I mean thats why Im asking people on this forum...for advice. Someone gave me the advice of going with vortec heads cause they flow good...but if you've got other stuff you've had on your build, Im all ears...

 

[4X4HIGH]

Is your block a "roller" block? How much $$$ are you looking to spend on this engine build? Are aftermarket heads in your budget? What will be the basic use/expectations of this engine?

 

[dyeager535]

And I'd say stay away from Vortecs if you want to run the stock TPI setup. Save yourself money and get some Aluminum AFR's or EQ's or something along those lines, that the stock base will bolt to.

 

[bigblaza]

And I'd say stay away from Vortecs if you want to run the stock TPI setup. Save yourself money and get some Aluminum AFR's or EQ's or something along those lines, that the stock base will bolt to.

So no vortec's huh?

The thing is I dont "have" to run the stock setup. I mean I got a setup off of ebay for 250 but I haven't exactly put anything together yet. Worst case is I clean it up and put it up for sale again, if I find something better. I think from what I've read, one of the biggest drawbaclks to the stock TPI is the long stock runners are restrictive. I looked at the LT1 intakes and maybe thats a better way to go...

Any recommendations on what AFR's to look for? specs?

Is your block a "roller" block? How much $$$ are you looking to spend on this engine build? Are aftermarket heads in your budget? What will be the basic use/expectations of this engine?

No I believe my block is a 1970 model so from my understanding it is not a roller block. But I thought you could get a retro-fit kit? Aftermarket heads are definetly in the budget. $$ isn't my issue, I dont want to blow $5000 on heads alone, but if that was spent on the entire build itself, thats ok. Im not trying to just blow money, but this is a build for education and fun. If I have to buy piece by piece over time cause they're too expensive all at once, then that is fine with me. Im just looking for good advice to put together a solid engine and get the best power I can out of a 383, thats pretty much the bottom line. So if you got ideas...Im all ears

uses? I'd say some offroad (no mud racing or rock crawling)but definetly gettin dirty.., beach (sand), Maybe hauling a boat around, and most of all an all around fun truck...

 

[4X4HIGH]

Well, sounds like you're ready to spend some $$$ on a good engine build so i can help you with that. I'll send you a PM later tonight once i'm home and have access to the info you'll need.

 

[bigblaza]

sounds good.

 

[dyeager535]

Get a roller block. They are cheap enough, sounds like you don't need a 4 bolt main block (just harder to find in a roller block). Could if you wanted to though!

Roller retrofits are garbage if you are starting from scratch. Aftermarket is too expensive, factory parts retrofitting can be done (apparently) but why, if you aren't attached to a particular core. Besides, the one piece rear main seals are another vast improvement over early blocks.

4x4High has probably got some ideas on the port sizes. I don't know much about the LT1 intakes, I just know it was talked about in the past. Probably cheaper than aftermarket solutions. Note that no modern intake system uses any sort of length like TPI. It may have worked then, but engines are much, much better with modern heads, valvetrain, and exhaust than they were when the 1st gen SBC/TPI stuff was designed. Look on thirdgen for the back to back 383 builds with and without stock stuff. I think you'll find the stock TPI builds are very poor compared to what they are with non-TPI parts. Obviously you have to really compare what the motors are built for though too...low end is important in trucks, most builds are oriented towards upper end power. But there really is no reason to restrict a motor to a certain RPM range if there is little to no tradeoff in the range that you TYPICALLY run at.

There are some smart ways to do the build that will save you costs in some areas (Vortec heads for one) which simply allows you to invest in better components that are necessary elsewhere. No point in getting $600 Vortec heads and a $500 TPI base for them if you could get some complete AFR (or whoever) aluminum heads and an LT1 Intake for the same cost. I'm just guesstimating some of the costs in my head, but you understand what I'm getting at.

Some of us have made the mistakes, some avoided the mistakes because they asked the questions first, and thought about the build intelligently.

You know, the other option is to go with a completely different motor, like an LS series, which you can get into for about $3000 as I understand...

 

[bigblaza]

Update...

Out of sheer stupidity I bid on an 99 LS1 block (alum) thinking there was no way I would win it for $200. Turns out I was wrong. I really had no intention of getting an aluminum block but after winning the auction I started exploring the possibilities of having a corvette engine in the K5..started to sound a little interesting. Then I started to think about what exactly would be needed for a LS1 Swap and realized that I have no clue about LS1 engines. I did a little research on LS1tech.com and all the various LS1 websites and am no fairly confident that I could do the swap. But what I still dont quite know/understand is the mechanics behind what needs to go into the actually build of the engine...

The engine was out of a 99 Vette with about 30k miles on it, has all the main caps (6bolt mains, didn't know that) and was in working condition when the vette was parted out. I was still interested in getting a stroker kit for this particular engine, but still haven't a clue on what heads or anythign else should go on it. Im not 100% convinced this is the best way to go but am open to the idea of shaving off 125lbs from the engine bay by going aluminum, not to mention the increase in MPG I've been reading about from these engines...anybody do this conversion before or had experience in this? or any suggestions of what internals? Is this a good idea??

 

[4X4HIGH]

You need to PM RyanB, he is the LSx swap master. He currently has an LSx in his rig and is building an LS6 vette engine now for it.

 

[dyeager535]

Yeah I suspect you won't want/need to modify the internals. What displacement is that one? (unfamiliar with the displacements used in cars)

I think $ for $ the LS series motors are the way to go. Only problem is, you'll need some sort of harness and all the sensors if that's gone, and it will probably be pretty expensive. $3000 for everything was the last I saw of a "decent" deal for an LS motor with electronics included.

Might have been enginemasters magazine (part of hot rod IIRC) that had an LS motor buildup not that long ago.

 

[jonrpick]

Yeah I suspect you won't want/need to modify the internals. What displacement is that one? (unfamiliar with the displacements used in cars)

I think $ for $ the LS series motors are the way to go. Only problem is, you'll need some sort of harness and all the sensors if that's gone, and it will probably be pretty expensive. $3000 for everything was the last I saw of a "decent" deal for an LS motor with electronics included.

Might have been enginemasters magazine (part of hot rod IIRC) that had an LS motor buildup not that long ago.

I was just thinking of the Engine Masters build...

Theres was carb'd wasn't it? I've heard of guys getting pretty sick numbers from the LS motors, even with a carb. I know there's a manifold for it.

Based on that, since you're changing directions, why not consider something simple like the carb manifold with a F.A.S.T. throttle body and injectors in the runners?