Serious Engine Combo Question...
 

Hey all,
As you know, I have a mildy modified TPI 305 in my '88 SS. It has World Products S/R Torquer 58cc heads with 1.94/1.50 valves, Crane Compucam, roller rockers, and SLP runners and ported plenum. I'm looking to make some more power, and will be acquiring a roller-cam 350 block in the near future. Here are my options -

1. 350, reuse the World heads (after porting) and TPI intake, and get a more agressive cam

2. 350, buy a set of used Vortec heads and rebuild them, get the SDPC Vortec TPI base, more agressive cam, and keep my TPI setup on top

3. 350, buy a set of used Vortecs and rebuild them, more agressive cam, and then bolt on the new Stealthram for Vortec heads that will be coming out shortly.

What will give me the best bang-for-the-buck? I think option 3, but I'm not positive. I'm looking for something in the neighborhood of 375-400 hp.

3 is going to cost you more than 1 but you get what you pay for... except for 2, which is a waste of money.
The stealthram is what I'm waiting for. I was going to convert my RPM intake into port injection but then I saw that was at the SEMA show so I held off. Once it comes out I'll be rockin it with a roller cam swap and might even pull the heads to do some porting myself. I think 400hp would be easy for with option 3, option 1 would still leave you with long tube TPI and like down 80hp or more :( . TPI is great for a 305... you know ,the engine they designed it for, lol. But it's SO air flow limited with the long tubes and no taper... so if your trying for 400hp option 3, if you could settle for like 350hp go 1.

Thanks Jon! I was hoping you'd respond. I was also thinking that 2 was a waste of money. The Scoggin-Dickey baseplate is more than the whole freakin' Stealthram. So, option 3 it is for me! Any cam recommendations? I was thinking of the LT4 Hotcam. And, will the MAF system be a real restriction in this case?

Now I just hope that 400hp doesn't scatter my World Class T5. :)

Yeah, that baseplate isn't what you'd call bang for the buck.
For a cam, Lt4 hotcam will work but why not a zz3/zz4 cam? The Lt4 hotcam would make a bit more power but not by a staggering amount. Really depends on exactly how much compromise. You'll get over 400hp with the zz3/zz4 cam and they can be had for just over $100 on ebay brand new in box. Not to mention the exhaust lift is right at .510" which might (or might not) be the max safe lift out of mild machine work to vortecs.
As for the MAF, it isn't a big restriction but it is one non the less. What's more restrictive is the code in the ecm. I'm assuming since you have MAF and TPI you're using the 1227165 ecm, that runs on $6E code which has been known to give people difficulty. At least the people that drive the cars often and know what it SHOULD drive like... (skidownit doens't know the feeling). The difficulty with $6E code is it's spark advance table. It isn't based on just RPM and Airflow like you would think (or want). Instead it's based on a load variable called LV8. This variable moves all over the place and overlaps with some areas that you want a discrepancy with timing. I could go into more detail but it might get confusing. So my vote is to run $32 speed density code in the 1227165 ecm. It doens't require much effort to run the code, just remove the MAF and wire in the MAP sensor. The only downside to running $32 code is the fact that the tuning needs to be done correctly and the ALDL data-stream rate is much lower than with the $6E mask (mask is another word for code if that's easier to understand). The alternative to the 1227165 ecm is the 1227730 which was used on the last years of TPI (91 and 92). It was also used in lots of v6 applications and this code is far easier to tune than the $6E.
So does that answer your question about MAF?
Your T5 should handle it so long as you don't powershift it on a regular basis. I actually want a T5 to beat around before I go T56.

After a few minutes of searching the 'net, I found a page with some cam specs. It lists the ZZ3 cam at 208/221 duration, with lift at .474/.510 (I/E). The Hotcam is 218/226 duration, with lift at .492/.492 (I/E). This is with 1.5 rockers. Both of these I'm sure would produce a semi-noticeable exhaust lope, which is pretty cool. :) The other thing I remember reading from my LT1 days is that the LT4 motor did not have an EGR system; there was enough overlap in the cam to compensate? Since I'm gonna run Vortecs (which don't have EGR ports) maybe the Hotcam will be better in the long run?

Ah, this makes sense. I like the idea of using the MAP code in the '165 (easier to rewire) but is there a way I would be able to use my AutoXRay scantool with a change like that? I will do some checking on Mike Davis' site to read how involved a pinout change is from the '165 to the '730 as well.

Thanks for your input so far Jon!

to rebuild vortec heads and buy used ones will cost you between 800 and 1000 dollars and a tpi intake manifold is something like 300.

iunno if i had world heads id just port them and get a better cam to that still matches compression and rock em. what cc chamber are they?

Not poking fun but he listed the chamber size in the first post, 58cc.
Where are you getting those prices for the heads? Yes the vortec tpi base is expensive, that's why I wouldn't consider option 2.
$680 or less depending on if you need the .600 lift, $650 for the .525 max lift heads. Grab yourself a porting kit from a generic website for like $10 (yes they are all the same and Summit just jacks up the price on these kits). Do the porting yourself to save money and go with the Holley Stealthram for vortecs when it comes out. I think that with a hot cam or the zz4 cam would work out really well and depending on the port job you'll see over 400hp. The worlds heads could support the same power but now you can sell them to pay for the vortec Stealthram :) . The vortecs have a better intake port design and the chamber is a better design. That's why I like the vortecs, they're lt1/4 technology for gen 1 engines only without that crappy EGR :wink:

Well, I'm picking up a set of Vortecs for "very" cheap plus a trade on some parts that I will never need. Even if I had $500 worth of work done on them, I'd be into them for under $700. And I don't think the work I need will cost that much :crosses fingers:.

True. Plus, I'll have my existing TPI setup to sell as well. The whole thing is powdercoated, and I have the SLP runners and ported plenum as a bonus. It looks good, and works well for a 305.

Man, this is gonna come together nicely! Thanks again for your opinions and ideas!

to make vortec heads accept any sort of lift around .500 you need to change the springs and with that you should do the seals, might have to make some room for the springs to fit. then you have to machine the guide boss down, then rocker arms for aluminum roller 15s is around 250 from summit. roller tip rockers arent really the best. if you decide to go with a stamped rocker you need self aligning ones, still expensive. stock rockers that come with vortec heads are garbage for any sort of cam around .5 lift. then after you get the springs and seals and do machine work and get the rockers you need to but screw in studs and guideplates would be a great idea. however once you do screw in studs you have to get the boss machined down to accept the new studs. we dont want pressed in ones coming out now. so even if you do the pressed in stud work yourself your still talking costly. even if the heads are only 100 bucks guideplates are 15 bucks, edelbrock springs for the heads with dampners in em are 100 bucks or so, dont wanan run cheap springs and have em break 30 bucks for studs, 38 dollars for seals and orings, and then you gotta add up machine work for em. plus the rockers for a good roller set your looking 225. oh yeah and if you go 1.6s you have to do some work to the heads too

http://www.sdpc2000.com/catalog/2172...-Head-Kits.htm
Great deals on already worked over vortec heads, still needs porting though.
I plan on pinning my vortec heads and keeping the self-aligning rocker arms. I don't see them being a problem unless you don't have a rev limiter and/or have really mismatched springs.

I agree with Prevo on option 3. The Vortech heads and Hot Cam are a proven combination over and over again. If I was building another engine I would probably go with a similar setup and save myself a lot of what I spent on my AFR's.

Also I can attest to the MAF system being a pain in the ass to tune on a performance engine! :?

I would go with the Vortecs and ditch the long-runner TPI. Vortecs are insane heads that dont quite get the true respect they deserve yet.... I bought mine for $300 and then put $150 of machine work into them: cleaned, new springs, and screw-in studs. Some people claim you cant go over .480 lift without running into valve guide to retainer clearance issues but mine had like .550" of clearance stock so I didnt get them cut down. Once you have screw-in studs installed you can put guideplates on the heads (no machining required) and run cheap non-self aligning rockers. So, at most you have a $500 head that is probably the best factory GM head ever made.

Where did you get your headwork done? I'l be picking these heads up sometime in February I think. They're '062 castings off a '98 Tahoe with 68K miles on them. I am most likely gonna go for the Hotcam and then get the Stealthram for Vortecs when it comes out.

I got my heads done at a little unknown machine shop in south jersey called R&R Machine. Even the worst machinist would find it hard to screw up the basic mods you'll need to have done to the heads. I also am running the LT4 valve springs you'll be needing for use with the HOT cam, although if I could do it over again I would buy a better spring (even though they work perfectly fine) I just dont think I can step up any further than I currently am with them.