So.. heres the deal.. Ive been buying parts for my car very slowly due to limited funds. It may take years to build due to lack of money and knowledge but one day my firebird will be on the road. For a long time now Ive wanted to build a 350 w/twin turbos.. About a year ago I bought and ported Accel base (from Kandied) and just recently I bought a set of AS&M runners (from another member on this board). Shortly after that I bought a ported plenum off somebody else. Now that I have invested close to $1000 in a plenum, base and runners Im wondering if these parts will work well with a twin turbo set up.... I have more questions but before I get ahead of myself I need these questions answered..

Thanks..


Dan

 

That should work well. It should flow decent and make a lot of torque down low still. Do a search for 89JYturbo and check out his twin turbo setup. He runs a stock TPI and pretty much a stock engine. I think he was pulling mid-12's with smallish turbos. I think he upgraded them but I have not seen any 1/4 miles times with the bigger turbos. The aftermarket TPI you have will flow a lot better and have better HP numbers. What is the plan for heads & cam?

You are doing it right by taking your time......that way you can come across decent deals on parts and learn more about turbos and what would work well with your setup. Buying stuff twice is a tough way to build something. You are off to a good start.

 

Its good to hear Im headed in the right direction. Im familiar with 89JYturbo and his cars. He and I belong to V6z24.com. Im MORE familiar with his J body than I am with his F body. As far as heads and cam.. well that was basically my next question. I figured if the parts I have will work for a TT turbo setup Id ask you guys what type of heads and cam I should go with. My ultimate goal is to have F-body that is a fun car to drive. Fun car (for me)= runs 12's in the 1/4 mile.. drive it on the street.. decently set up for auto xing ect ect. Lastly.. I hear a lot of people talking about extrude honing.. Whats the difference between that and porting??

Dan

 

Imagine taking a really thick, gritty tooth paste and forcing it through your plenum/runners/heads, etc... That's extrude honing. Porting is done by hand or machine with grinding wheels/polishers.

Heads and cam is not nearly as important if all your looking for is mid 12's out of a TT TPI. You should be able to make enough power to pop the bottom end with the stock heads/cam and the turbo's. IMO, doing the heads and cam is kind of pointless unless you plan to upgrade the bottom end at the same time. Here's an over simplified way of looking at it:

To go 12.5 it takes 400 HP.

Stock you make 200 HP. With 10 psi of boost, you will make 400 HP and go mid 12's.

Aftermarket heads and cam, now you make 300 HP without the boost. Now you only need 5 PSI to make 400 HP and go mid 12's.

What's the difference between the 2 combo's? They both run mid 12's, and one guy saved a bunch of money and labor by not doing a heads and cam swap.

As long as the intercooler(s) are up to the task, just turn the boost up to make more power. If you're trying for a max effort style of build, then the heads and cam become much more of a player, but for mid 12's the stock stuff and 2 turbo's should get you there no sweat.

Good luck!

 

thanks for the info neat..

Where to begin... where to begin.. (more questions)

I really dont have a reason WHY I chose mid 12's... its just a number that I came up with at random. Thinking about it now I guess I should have a FIRM number in my head before I get any further. I can't really come up with hp/torque #'s. I hate to put it this way but if I had $1000 to $1500 to spend what would you guys recommend for heads and cam combo? Also Id like other opinions on my base, runner and plenum set up.. Good? Bad? So so?? (I just want a general "thumbs up") Anyway back on topic... Orginally I was gonna just run the car with the "new" base, runners, plenum and AFPR and see how I do at the track. Well... at least one year went by (brings me to present day) and I was looking at everything that I have and figured I might as well go with a cam and a set of heads. Now Im thinking that if I order a set of heads and a cam I might as well go all out! (block, pistions, crank ect ect) lol. I dont wanna order a engine block yet because I dont have the room for it. I figure I have the room (and money presently) for a good set of heads and MAYBE a cam. As far as extrude honing vs. porting.. is one better than the other as far as optimum performance??

 

You can run mid 12's with forced induction on a set of stock heads and cam, so if that's your goal, take your time, build the turbo system, and save your $ until your goal moves to mid 11's (or better yet - road racing!) I used to be in the same situation. I had a stock L98 that had blowby issues with the turbos, so I figured, why not freshen things up? If I'm taking the heads off already to put in better pistons & rings, I might as well upgrade to AFR 210's and a bigger cam. Now that that's not bottleneck, and I drop compression down to 8.1, I can turn up the boost, so I need a forged crank - OK, Callies Dragonslayer on the way. The pistons should get a thermal barrier to help them last, so call Swain Tech, get them coated, and have Anatech do a DLC coating on the wrist pins. Since the rotating assembly is now strong, I should have a block that can take it, as it'd be a shame to lose several $k in parts due to a block distorting or cracking, so the Dart Little M arrives.

In other words, once you start down that slippery slop of: "While I'm at it, I might as well...", there is no end. Be very careful! I originally planned on a $3,000 budget build. Hah!

 

I just got back to Andris' shop, and needless to say- his budget build up has now become a crazy obsession. Definitely a bulletproof set up.

 

I know what you guys mean. I stayed out of that "might as well" somewhat decently though, but after toiling back and forth about it endlessly. I think I ended up with a decent mild setup that would accomplish metalhead's goals nicely.

Don't even worry about heads and cam if 12's does end up being your goal (at the most go with 1.6 rockers).
I'd rather have a better bottom end first. Mine is a stock rebuilt and balanced '89 L98, but with GM powdered metal rods, Speed Pro forged dished pistons, 9:1cr, and ARP hardware.
It wasn't that expensive, but will allow me to safely run more boost than the stock engine would have. That, with your upgraded TPI and two intercooled junkyard T3's (the bigger ones ideally) would be capable of very easy 12's on pump gas and would spool very fast too. That would be a very fun street car.

OTOH, if you go all out like Andris, be prepared to scare yourself.

Good idea taking your time, but realize time flies still and before you know it, you'll still be out of time. Ask me how I know.

 

$3K budget… my suggestion is to just not look at the receipts, your sanity will thank you for it. I gave up when someone commented that the back of my fullsize blazer looked like a speed shop exploded in it (which is seriously impressive for someone that doesn’t tend to spend real money on parts but more often then not tools to built the parts himself), and right now I’m just looking at adding all good stuff on top of and in behind a junk short block and once I get that together I’ll try not to carry it home in a bucket before I put together something serious for a short block.

Hey Andris, how much horsepower do you actually think you can use on a road course? Last year I ran a few autox’s and got a serious bite of the handling bug again. For my project I decided to go with a 4L80e (but I am building my own paddle shifter setup for it), mostly for safety/sanity reasons (think carrol shelby and his supercharged 427 cobras), but I’m seriously thinking of trying to get back into some high speed turning.

 

As far as what appears to be a TPI + boost question… well, I don’t see a really good reason why properly setup you couldn’t get a proper boosted TPI small block into the 800hp range. Even a stock L98 with some boost should be capable of probably just short of 600hp (on race gas)…

 

For mid-12s I would use a stock 350ci TPI or a stock 305ci with a cam and some ported stock heads. Probably treat it to all new gaskets and bearings. I would go with a Master Power T70 or GT45 or Garrett diesel or Holset diesel with a Tial 38 mm wastegate sitting on a modified stock exhaust manifolds or a custom weld-el manifold. An intercooler would be optional or maybe a cheap Ebay/Mishimoto IC.

This is just my opinion on how I would go about. Overall, a reasonably cheap setup. That is just me though. I love buying nice new tools, but hate buying nice new parts. You would be surprised what you can get away with when something is adjusted/tuned properly.

 

Thanks for all your info guys but my pervious questions have not been answered..

As far as extrude honing vs. porting.. is one better than the other as far as optimum performance?? (Just wondering)

And I know SOMEBODY out there has a good head and cam combo for me.. lol I cant (in good conscience) turbo my car "as is." Presently its got a used "low mileage" 305 TPI in but Im sure that its seen a lot of abuse. I can just imagine my pistions and pavement having what someone on here called an "intimate encounter."

Dan

 

I used vortec heads on my 350. Crane claims their Powermax cams are optimum for mild-turbocharging. Thats what I used. I don't know much about the best options for 305 heads.

 

I'll let you know here in about 4 weeks..
Motor
-255rwhl, 352ftlbs torque 305ci
- Ported stock heads
- Compucam 2030
- Ported factory base, pleneum
Turbo system:
Twin Garrett -57 Turbos. 63 a/r, two 38mm gates, Mallory Boost timing computer, additional injector controller with CNG injectors,
air-to-water intercooler, HKS blow/off valve, all through the factory MAF sensor...

Hopefully it will make more HP than my Turbo-Hayabusa!

 

Twin turbo to only run mid 12's... I think people will be stuck saying, "You mean to tell me, you have a V8 with twin turbos and it only does 12's??" The cool factor is there though with having turbos

 

Yeah, that is true. But you get the benefits of good MPG and idle. You also get the benefit of saying my stock worn out 350ci with 100k+ miles that cost $1500 just did 12's. The N/A guys with $1500 AFR heads really don't like to here that. How many stock engines are capable of 12 second runs?
The other thing that people think is that twin turbos are "faster" than single turbos. There is no truth to it but that is what many people think.


The honing vs. porting question was already answered early on. As for heads, go with AFRs. I would call Cammotion and Comp Cams for the cam to use. No one can really give you a good heads and cam estimate with the tech. non-information and small amount of goals you have given. It is like asking "can I run 87 octane in my race motor?" Most will say no as a general rule of thumb. The general rules will get you in trouble though.

 

Yeah, with two turbos pulled from a junkyard you can make an L98 go mid 12's without pulling a valve cover. With only 6psi and on a stock suspension. But I do have people ask me why it 'only' goes mid 12's. Usually by people who drive 15 second Hondas Then I tell them I have a Cavalier that will beat them by 3 seconds in the 1/4 and I have a $50 to prove it.

But anyway, back on track.

Dan, if I'm reading this thread correctly, you feel as though you have to rebuild your engine before you do the turbo system? If you are really into turboing your engine, I would like to see you cut your turbo teeth on a tired 305. Maybe you can even sell your accumulated TPI parts to fund the turbo system since you are working on a tight budget. There is a guy over on TM that runs deep 10's at 128MPH on a STOCK TPI intake (only intake upgrade is a 58mm TB). He runs 22psi (!) from two GN turbochargers. 573RWHP; 662RWTQ. The long block is built, forged pistons, and mild ported Dart 200 heads. His motor is a low RPM machine, he's shifting at 4800rpm! Just shoes that the stock TPI can really run with a little positive manifold pressure.

Once you start to learn what you are doing, then you will be set to build your new engine to meet your goals. I wouldn't suggest learning turbo engine tuning on your fresh, expensive engine, especially when your budget is really tight. You won't have to feel too bad if your tired 305 chucks a piston.

If you really need to go deep into the motor, make it worthwhile and shoot for 11's at least

Hope that helps.

 

I like that. Must be running 44" Interco boogers to hook up off the line. I have to check that thread out.

In terms of the original thread topic. I would do what 89JYTurbo said. It is good advice.