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I'm rooting for ya! I've had a couple fun times with boost on my 305 in the past. Was funny to run a pass without a wastegate spring, a 14.5 e.t., and then at 12-13psi the next pass pop a little wheelie and run a 12.2 e.t. It has a 204/214 cam in it and is untouched other than that along with the intake and exhaust obviously and spooled my 91mm turbo EVERY bit as good as my other motor could.

 

You spooled a 91 on a 305 with only a cam? When did that come in at? ANy other particulars carb TPI etc? Definitely listening.

 

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You can spool any turbo....but to do so will require rpms. My buddy spools an 88 on a 293" motor....it comes on hard by 4500 rpms probably making good boost in the 5000 rpm range and carries peak power to 7500 rpm. Thats over 700whp on that setup.

To do that on a 5000 rpm peak power TPI based motor, it may not happen....

 

I used much stuff from my other motor: 105mm throttle body, 95lb injectors, super victor intake. The OVERBOARD throttle body and injectors hurt drivability cause it'd often tend to stall just off idle and it would fall on its face at 100% throttle while it was happy at 75%. Either way, the converter would stall at 3500rpm on the trans brake until some boost was made and the motor would creap its way up to 4000-4500rpm in ~4-5 seconds on the trans brake. This worked fine with the 305, but the converter couldn't hold the other motor under 6800rpm while in boost so I was over reving the engine basically the entire 1/4 mile.

I have since gotten a tighter converter that stalls at 2900 on motor, 3200rpm with a couple psi and pretty much doesn't let my current motor build boost. I have a restalled converter on the way that'll stall 3500rpm on motor and creap up with some boost, but still should not be as terribly loose as the previous converter was.

If you intend to pull any better than a 1.800 60' time, I doubt you'll be able to do it on a foot brake since you'll likely need 3500rpm+ under heavy throttle to get it to launch in boost.

 

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mmhmm very interesting thread, good luck!!

 

updates?

 

So were going single turbo now? Or were you just thinking out loud?

 

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What? new polished alternator. Man, I would have saved that cash for upgrading the stall converter. Looking Great so far. That block cleaned up nice.

 

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maybe a missed it but do you plan on running 9s on a stock 305?

 

On some of the later model blocks there is an oil pressure port right above the water pump below the intake manifold closer to the passenger side head. But I see you dont have that. That would be a nice place for an oil line as well

 

Yep you missed it.

This build like most budget builds are all over the place as parts come and go but I don't think anyone's mentioned stock here. There is nothing stock about this build that I can see.

If that alt works don't waste money replacing it. You should see the alt on my 86Z. It's been working in the car for 9 years now and has always had chipped fins and looks like hell, the stud in it cracked and it lays against the bolt in the bracket held there by the belt. Most guys would have replaced it years ago but it works great, cosmetics are illusion.

 

man, I wish I was paying more attention to this since this is so close to my TA build (starting with an '87 LB9 with wasted heads and 110K miles on the engine, cleaning up some old 416's that I have in the basement with even more miles on them... The biggest difference is that I'm going single turbo, either an HX52 or a GT4202 that I have sitting around and I'm debating using a vic jr that I converted to efi years ago, of course, I have 3 TPI manifolds sitting around that I may end up using instead).

What cometecs are you using? Do you have a PN/specs? I've been having a bear of a time trying to find appropriate head gaskets.

What's the lift on the cam that you're using? Looks like you left the pressed in studs, no guide plates... in the 416's, and didn't convert to PC seals or do anything special with the spring pockets... you have me wondering there.

I'm not sure about the cam discussion... funny, I had a similar one offline with junkcltr and I ended up on on the other side of this, where he seemed to be leaning smaller cam and I was debating a bigger one (I really want to run a 280XFI, but the lift is just boardarline too much lift for anything that I can make the heads do easily, so I'm likely to use a custom grind that I have in the basement using 224/224/114 XE lobes, but I'm afraid that it won't be enough cam for what I want out of the little 305)

 

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I was just saying to a friend how I wished I would have done this with my 305. I had RHS stock replacement heads on it, intake, 1 3/4 headers, an LT1 cam, and about 16 psi from my s-trim. With a stock stall converter it was beyond crap on the bottom end, but it pulled nice right around 4000 rpms. Even with 2.73 gears it would start smokin the tires at high rpm in first. The trans didn't last long, but the car was sure fun on the autobahn!

When I got back home I tore the motor apart and it was real clean and I never found any signs of detonation. 7:1 cr might have helped that, but I just got lucky I think. The tune was off many times, but timing was always low. Anyhow, I'm sure it would have been an 11 second car and it was just slapped together and driven twice a week to base. Never would pass German inspection though.

I'm looking forward to seeing how this works out for you. I have a super light stang tube chassis that I've been thinking about propelling with JY 305 motors.

 

Man, This and Atilla's new threads are making me want to save my 383 build for another car. And maybe pick up some nice heads and up the boost and get a real tune on my LB9.

Sorry to go off topic but. Street, whats up with the GTA. Any new times yet with the added boost?

 

yea, I have a converted LT1, and I haven't considered it because I feel that it isn't a great setup for a boosted setup. The LT1 guys tend to have problems with 7, then 5 and finally 8 going lean with big boost, because the're in the back of the plenum getting a straighter airflow shot than the front cylinders so they get more air...

What thickness did you end up with?

I'm much more worried about getting good quench and decreasing crevice volume than I am about shooting for a specific compression. The LB9 is supposed to have a 9.3:1 compression, and most people seem to say that they work out closer to 9.1, so with a slightly cleaned up chamber I'm hoping to see roughly 9:1 or less, which should work fine. I don't want to drop compression too much with that big a cam in a 305.

so what are you doing for guiding the rockers? Using the stock broached holes or what? 322# springs will technically be enough to pull the studs, but it will probably survive a few runs before it happens.

 

I hear that too. How much does a TPI plenum, LM7, and other TPI derivatives differ from the LT1 plenum really? not much. I think the LT1 guys have problems because they start out with an 11:1 CR and boost it until it blows. On top of that they do the Hack MAF tuning with PE mode. It goes on and on........stock LT1 and stock LT1 ECM are a poor choice for boost and people blame it on the intake manifold.

I would put the LT1 intake on it before the TPI intake if I was trying to hit 9s. Either way it has to run way rich to make up for distribution problems regardless if it is the TPI or LT1 intake. With the 305 and cam being used I think it will take over 26 PSI with the TPI intake to get it into the 9s. If you look at the dynamic compression it is deep into the danger zone. Cometics to the rescue.

 

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The great thing is that if you're looking to experiment with an engine these are available for next to nothing. I have about $300 into this short block, the next one will probably be about 125-150 that is including head gaskets and bolts! I mean I realize I'll need a cam and some heads but for the price I can lose an engine and/or build up engines easily enough to experiment with a wide variety of things without hesitating about it.

 

Subscribed!

Awesome build up. Much credit for just pressing forward and getting it on the street while other slackers like myself get caught up in getting high $ stuff we don't need and turn our cars into storage shelves.

What an awesome article referenced here with Marty and that 88TA. Starting out with high $ AL heads and stuff, then dumping in a 150k junkyard motor and getting in the 9s!

Let us know what you may need so some of us can maybe help ya out with our junk laying around.

PS. Keep it's 15th Anniversary Roots Please!

 

While I agree that 11:1 compression and crappy tuning being some of the problem, the fact that consistently the same holes blow on them is a pretty good argument for a distribution problem. I can definitively say that I've never seen a heavy breathing LT1 hurt any of the front cylinders and it's _always_ been the rear ones.

As far as cometics to the rescue... whoohoo... a headgasket that you can't push, so instead you pound the pistons, ringlands, rings and bearings into dog ****...

that's much better than spending a few $$$ and hours replacing a set of gaskets. If I could find some with the right bore and thickness I don't think I'd consider the MLS style gaskets...

 

LT1 is SEFI which can be and is tuned per hole. Why would only certain holes consistently blow if tuned properly? It leads me back to 11:1 and people that turn up the boost without tuning properly.
I have a 1995 alum. head LT1 sitting in the garage that I bought off someone to help them out when they needed cash. No matter how desperate I get for a replacement turbo engine that thing will never end up with compressors on it. They were GMs experiment to fill the time gap of the LSx series.

As for the cometics, he isn't looking for an engine to replace gaskets on like you or I would want. He wants to keep turning it up until it is not worth repairing.

Any updates on the build?

 

I have read they add 8% in a stock tune to the rear two cylinders even N/A. Honestly all intakes will have some sort of distribution issues but at the same time that does seem a bit excessive. Then again that is why people use EGT probes in all 8 cylinders for their super high $ race engines.

305 short blocks are cheap. I have 2 here for under $100. The cam would be the worse loss IMO. Then again as long as he keeps it safe I wouldn't foresee the need for cometics. I mean hell that is actually 1 place the 305 has an advantage compared to a 350, it has over 1/4 inch more sealing for the piston on the HG.

 

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And this is one of the reasons so many people will enjoy reading this thread. Many of us are right there with you running the JY stuff, but you are going a step further. Keep up the good work.

I think I used a stock TPI brass TEE for my setup. It was the right height. One side was the fuel pump oil pressure switch and the other was the oil pressure to gauge. I added another TEE on one side for the oil pressure to the turbo.

 

I might have missed it, but what are you going to run for an ecm? Will you be able to trim the fuel on individual cylinders?

Are you trying to keep the motor as factory as possible? I think if I do use a 305(s), I'll use a single plane for cylinder consistency.

 

Subscribed!!

I can't wait to see it run, and then blow!

Good luck!

 

I was gonna suggest the turbo forums about Marty Stromburg, but seems he already a celeb already round here. Few years ago Hot Rod had a list of cars they had for a race, and one Camaro had a t88 turbo, a 305, and his time posted was in the mid 10s. Love all the jy builds they are so cool.

 

Love the 305. I always hear people say you need a 350. Well here ya go i wanna see what this baby can do. Fun stuff right here.

 

Wow, Street!
Thanks for the cometic custom gasket info!! That fellas, is some info we can use! Question is how much do they run??

 

Hopefully she works out for ya. Sounds like a real task you got ahead of yourself. My 15th came with a 350 in it from a previous owner, and a t-5 was swapped into it. I wanna drop a real-deal pontiac motor and 4-speed in mine, having some ugly 'corporate' motor and slushbox t-5 just doesn't cut it for me. lol

 

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Can't wait to see more!!!

 

Did you end up welding or brazing the EGR passage in the exhaust ports?

 

im very interested in this build. I am planning on running a 305 with a turbo. not going for 9's. Just low 11's

Have to run a carburetor since the only EFI stuff I have is off of a mustang

 

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