Destroked LS2

[DJW32]

This is what I'm thinking about
I'm looking for 750-800HP

How about an aluminum LS2 with a 4.8L crank, 6.0L heads with crane cam springs, edle. intake,forged internals, and a twin turbo setup (2 hi-fl 61 turbos, this is subject to change for whatever will work in the most efficient manner)
Questions:
1. How many cubic inches is that(364 cubic inche LS2 with a 4.8L crank)?
2. What will I be giving up by destroking the motor?
3. How high can I spin the motor?

Thanks, David

[Nine Ball]

I gotta ask why when considering destroking an LSX engine.

1. Any gains you hope to achieve in with making it more oversquare would not exceed the potential limits of the block itself, when speaking of a boosted setup. You will lift the heads under enough boost (around 900 rwhp or so) even with a stroker crank.

2. You aren't really concerned with the higher revving characteristic of an oversquare engine, since these LSX engines can pull past 7000 rpm no problem with a hydraulic cam. My LS2 in the Corvette pulls to 7000 rpm with a 230/230 114 cam and stock unported heads.

I'd leave the stroke alone, and just let the turbos do the work. You can even run a cast Eagle crank and save some bucks. The block will be the limiting factor in that combo, not the crank.

[DJW32]

Tony,
The post is only a theory, I should've mentioned that...
Thanks for the feedback...I'm always looking for opinions

[Kenova]

Assuming you use the standard 4" bore: 328.23 cu.in. If you want or need a 5.3L engine this combo would have a slight advantage over the factory 5.3L when it comes to breathing. The larger bore will help unshroud the valves and/or you could use bigger valves.
The 4.8 con rods are longer to make up the difference in the shorter stroke so you could probably use LS2 pistons.
Yeah .... I've given it some thought too.
Ken

[rocketman]

I built a destroked LS1 for a guy in town,it came out to a 302.i don't rememeber I think it made 575 hp,It's a very high windy engine.I know we turned it 9g onn the dyno.he did it for the 302 combo in a z/28 think.

[DJW32]

rocketman,
Do you have any pictures or a dyno graph...

[rocketman]

When I get back to the shop next week I will look.

[gEtyOpAPiOn]

hmmm i did a search on a destroked ls1 to make it into a 302 for a z28 that i wanted to build but i came up empty handed ...what crank and rods did you use rocketman ?

[SLED28]

This is what I'm thinking about
I'm looking for 750-800HP

How about an aluminum LS2 with a 4.8L crank, 6.0L heads with crane cam springs, edle. intake,forged internals, and a twin turbo setup (2 hi-fl 61 turbos, this is subject to change for whatever will work in the most efficient manner)
Questions:
1. How many cubic inches is that(364 cubic inche LS2 with a 4.8L crank)?
2. What will I be giving up by destroking the motor?
3. How high can I spin the motor?

Thanks, David

I would stick with a 347 motor or the 364 LS2. Turbo's like stroke, a 3.900 stroke or 4" stroke would be even better. It helps them spool. Many years ago I built a 347 with a single turbo and it made 815rwhp. So either way you are good but I would not de-stroke it.

[rocketman]

hmmm i did a search on a destroked ls1 to make it into a 302 for a z28 that i wanted to build but i came up empty handed ...what crank and rods did you use rocketman ?

Callies 3inch stroke crank
sleeve block to 4inch bore
i cant find my file on that motor,i dont recall what rod we use,it was a billet rod i dont recall length.

it was copy of the yearone 302 ls1 they did back in 01.

the motor had i did had 12.1 comp and a solid roller with ls6 heads.

when i find the file i will give you all spec's.

[DJW32]

Rocketman,
I have thrown the turbos out of the equation.

Was that 575 horse to the wheels?
Do you remember the torque curve?

[rocketman]

No that was motor,tq was only 400 if that,it's not a tq maker.I for the life of me can't find that file.It has no bottom end to it.

[rocketman]

If you want a nice ls1 i would build a 393.make's nice hp and tq.

[Diognes56]

Example of destroked LS1 .

http://www.ultimatecarpage.com/frame...hp&carnum=1147

David

[DRCE]

Turbos like stroke plane and simple. I have always followed the plan of building the largest engine possible for a turbo application provided it was within the efficiency area of the turbo/turbos still.

A like doing 408's in iron form fairly often for boosted stuff, coupled with an 88 or a pair of 63's your in good shape and it will make a boat load of power.

[chuntington101]

looking at a few vettes and cameros, i would go with a stock inch LS1 with good internals and go for it!

you should beable to make 1000bhp easlily (as easy as it is to make 1000bhp! lol).

thanks Chris.

[Fuelie Fan]

Turbos like stroke plane and simple. I have always followed the plan of building the largest engine possible for a turbo application provided it was within the efficiency area of the turbo/turbos still.

A like doing 408's in iron form fairly often for boosted stuff, coupled with an 88 or a pair of 63's your in good shape and it will make a boat load of power.

I think that should read "driver likes stroke." EVerything being equal, more displacement equals more power, and that's always good! But, there's nothing about stroke itself that makes turbo matching difficult. You can match a turbo to a 327 just fine even though it's got less stroke than a 383. HOWEVER, if you're reducing stroke with the goal of drastically raising an rpm limit, then you have a bit larger challenge on your hands. Centrifugal compressors have limited ranges within which they will work well (I trust most of us have seen turbo maps), so asking a turbo to be responsive from 2000 to 8000 rpm is much more difficult than getting response from 2000 to 5000 rpm. This is NOT just a stroke thing, this is an entire engine combination thing (stroke, cam, intake, heads). So, what it should actually say is, "turbos don't like extremely large variances in airflow rates."

[RobM]

destroked engines are built to work in a narow powerband any way. if you want an engine that makes power below 5k dont waist your time. your building the wrong tool for the job.

[Fuelie Fan]

Yeah, in the context of this thread I'm not disagreeing with DRCE. At the same time, engines with "short" strokes can ALSO make huge power with a turbo and still be very streetable. It's all relative; the 327 is a stroker compared to a 302! I just think there was some oversimplification that I thought I might elaborate on. If somebody is starting out with a 327 which isn't already set up for high rpm performace, (maybe it's their numbers matching 275hp motor?), I don't think they should feel compelled to stroke it to 383. I take that back, I would endorse it, just as DRCE does simply because it's easy power...but my point is that such an increase is due to DISPLACEMENT, not stroke.

Put another way: Is a 307 a better turbo platform than a 302 because it's got a longer stroke? (i know...the tiny bores shroud the valves, but if that weren't an issue...for the sake of conversation)

It reminds me a little bit of the 377 vs 383 debate, and the ensuing hot rod article (which now I can't seem to find) in which the two performed almost identically, going against all pre-test speculation. Had they turbocharged them, I suspect the result would be the same.

Anyway, my original post and this post are both probably not of interest to original poster who was interested specifically in destroking his engine, to which the correct response to question #2 is along the lines of DRCE's. removing displacement reduces the amount of possible peak torque, whether it be through a reduction in bore or displacement. To compensate for this and still make the same horsepower, you need to increase engine speed (hp ~ T * RPM, so if T goes down rpm must go up). Because reducing the stroke reduces piston speed, this approach is the most viable (as compared to a small bore long stroke) for raising the engine's rpm potential. But in order to match that, you need to time the valve events differently (in other words, run a more aggressive cam). Doing this will cause a FURTHER reduction in low end torque. PLUS, now you've made your turbo matching more difficult, and if you match it for top RPM/peak HP numbers, you'll have more lag down low, making the engine fell even weaker yet off the line. All of this adds up to not removing stroke if you don't have to in order to meet the rules of some sanctioning body.

[SLED28]

It is true, STROKE drives the turbine faster. Look at the 449 fords out there, all stroke, running 6's on 10.5's!!!