Too start my lt1 engine had ran great up until about a week ago. from numerous times over-revving ad showing off i managed too wear the lobes off the camshaft. I've bought just about every part that bolts onto this motor brand new in the last month. I was going too build a 383 stroker but a local engine builder convinced me that he could rebuild my motor too a 358 port and polish the heads , new valves rr springs lifters pushrods and port and polish my intake and believes it will dyno well over 400hp at the crank. i told him i wanted lower compression because in the future i wanted too add a s/c or t/c. the rebuild also comes with a custom grind comp cam that i wont know the specs on until we sit down and discuss the build. this guy has been in business for 40 years and its entirely family owned. i've never heard a bad thing about his motors except for the time it takes him too complete the build. he said it would cost anywheres from 2000 too 2500 minus the rr's. he said i would have too pay for them seperate. is it plausible that i could get my motor rebuilt for this cheap and not sacrifice on reliability? will these motors rev high and pull like a 383? i know the ones in the dirt cars that he builds will but they are 13 to 1 compression and will only run on cam 2. i cant afford 8 dollars a gallon in my daily driver. im on a budget here because my 2004 chevy tahoe is burning oil badly and ticks on cold starts. any info on the 358 is greatly appreciated

 

How does he plan to get to 358ci? Bore it 0.050" over with the stock crank, or use a 3.50" crank with an 0.030" overbore? The question I would ask is why use up the cylinder walls going to 0.050 over, when you will notice no difference between a 355 and a 358?

With regard to compression ratio, its not simply the static (SCR) that determines the fuel octane requirement. Its the dynamic compression ratio (DCR), which is a combination of the SCR and the cam events. Put a big enough cam in it and you can run high SCR on pump gas. But is that what you want for a daily driver?

 

I think his intentions were too bore it. .030 over. If its only a 355 that's fine with me. Why would he say that it would be a 358? Is it because our motors aren't a true 350 ci motor?

 

I hope he's not reusing the crank because I plan on boosting this motor next winter. And using it as daily driver this summer. Will I have to change cam and heads once I add forced induction?

 

The LT1 is a 4.000" bore x 3.480" stroke = 349.85ci.... pretty close to 350ci. With the 3.480" stroke, 0.030" over will give you 355.12ci. This is simply a 350 SBC with an oddball distributor location and a reverse flow cooling system.

When I had my stroker built, we limited the overbore to 0.020" (380.77ci with a 3.750" crank) to keep the cylinder walls strong for a 300-shot of nitrous.

What you need to do when you add forced induction will depend on what cam he picks. You don't want some sort of radical 108* LSA and the corresponding overlap, with a blower.

By "stock crank" I was referring to the stock 3.480" stroke. If all you were doing was a 355 with heads and cam, the stock crank, radiused and polished would be OK. With a lot of boost, you obviously want yo use a quality forged crank.

 

As Fred posted, definitely find out how he intends to come up with 358cid. If you are going with all new internals it makes sense to get a stroker crank and add some torque to the mix. A stock stroke forged crank won't be worth anythnig except more strength, especially n the snout area if you are going to do a centrifugal blower down the line.

If you were going to go turbo I think you could probably get away with a stock crank although I would still opt for a forged crank just for peace of mind. I also opted for only a .020 overbore when I built my first engine but .030 will be OK. Just be aware that if you ever hurt the cylinder walls you may need a new block. I don't think that is a huge deal since LT blocks are dirt cheap.

One more thing to think about is compression. If you really are going forced induction later you will want to keep the compression in check, I would go no higher than 9.5-1. But honestly I think if you only want 400 crank (or flywheel) horsepower that a 9.5-1 of any cid (350,353,355,358,377,381,383) with ported heads will get you there no problem and allow a blower or turbo later. Hell most stock headed LTx cars with pretty much any cam will touch 400 flywheel horsepower.

Good luck,

Larry

 

Im assuming for that price he's gonna reuse the crank. I should just spend the extra. And buy a new one. The reason I mentioned turbo is because im already halfway there. I. Have a T3/t4. Hybrid jdm fmic greedy bov external wastegate. Tons of 2.5 inch I/c piping. I have a 88 third that I lost interest in. I figured these parts could be put too use on some real muscle. Im gonna go down too the shop and have him give me a spec sheet on exactly what he's going too do.
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2500 for a turbo engine without the turbo. Seems a bit cheap to me. You need to get the sheet from him. I bet he is using lower quality forged rods/pistons, and going cheap on everything else.

A custom cam alone is big dollars my guess is $250+ (more like 300+ IMO)

 

Im not sure. I plan too add forced induction at some point over next winter. Can't you run boost on a stock lt1 at small levels? My tbird was good too 18 lbs of boost. Some guys were running over 20 at turbotbird.com I know the 2.3 was built with low compression and was meant too handle boost. I would think u could get away with 5-8 lbs on a lt1 with new stock internals. Correct me if I'm wrong but with beefier rods and pistons along with new main and rod bearings I think I should be ok for what I plan too do. Im not aiming for 600 rwhp or any thing just a dd in the 400-500 range. I have no experience with turbocharging a v8. Is it true you have too mount the turbo way down the exhaust because of the lack of space under the hood? For now I want a 400 hp daily driver w/o the turbo which I've heard can be accomplished with a good cam heads combo. Im going too use the stock heads with 1.6 rr's and all new valves springs retainers lifters pushrods. These guys are machine shop wizards in this area and will be matching my intake too the heads also. I already have every bolton imaginable. I have a 700r4 that's rebuilt about two years ago.
Stock 10 bolt with richmond 4.10s. Not very good on gas but the car pulls very hard. I wanna make more power so can keep the acceleration without sacrificing top end speed. Will probably go back too stock gearing once it is done.