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I'm a newb to LS engines but I have experience with the old school. LS engines are the sh*t, and I am thirsty for knowledge and wanting to come up with the best performing combo for autocross/road racing with occasional 1/4 mile racing.
I think it's been established in this thread that the best bang for buck is LS1 with Procharger boost vs. LS3 stroker:
Once I wear out my stock LS1 with Procharger and boost, I'm thinking about either a forged LS1 short block to take its place (with more boost) or...(gonna get flamed here) a destroked LSx running even more boost.
I'm thinking the large bore/short stroke would yield a mechanical leverage advantage.
You can have a very reliable Procharged setup on a stock LS1. You just need to make sure you have an adequate fuel system to feed it, make sure the tune is good and safe, and run a safe enough compression ratio based on what type of fuel you're going to use. There are plenty of guys on here making 650 to 700 rwhp on stock LS1's with a D1SC Procharger setup. That should be more than enough for an autocross, road racing, 1/4 mile drag car.
You can have a very reliable Procharged setup on a stock LS1. You just need to make sure you have an adequate fuel system to feed it, make sure the tune is good and safe, and run a safe enough compression ratio based on what type of fuel you're going to use. There are plenty of guys on here making 650 to 700 rwhp on stock LS1's with a D1SC Procharger setup. That should be more than enough for an autocross, road racing, 1/4 mile drag car.
Thanks for the feedback. The Procharger definitely seems the way to go.
So I've been doing some 'back of the napkin' calculations.
Normally, a longer stroke gives a mechanical leverage advantage (well, it ALWAYS does if the force on the crank's rod journals doesn't vary when comparing different stroke lengths).
However, cubic inches being equal, a larger bore can produce more torque on the crank if the bore is large enough. However, it would not be very cost effective.
Using an LS7 block with 4.125 bore, you could build a 349 ci using a 4.8L 3.267" crank.
Assuming compression ratios are equal between this theoretical engine and an LS1 (therefore peak cylinder pressure at detonation is equal), the theoretical engine would place more rotational force on the crank even while having a shorter torque arm (shorter stroke).
Again, I doubt that anyone would want to build this due to the cost, but imagine how that engine might perform if you were constricted to 350 ci!! More torque and way more rpms/high end HP! Also, this engine would likely see improved fuel economy over an LS1 due to longer rods causing more dwell at TDC and more complete efficient combustion of air/fuel mixture.
When restricted to X amount of cubes the above is definitely superior, but there hasn't been a whole whack of those combos made because there's really no reason to restrict yourself to the lower cubic inch. And I would assume this becomes even less important with FI.
It's like comparing the Chevy 302 to the 305, one can be a monster and one can be a nice boat anchor.
When restricted to X amount of cubes the above is definitely superior, but there hasn't been a whole whack of those combos made because there's really no reason to restrict yourself to the lower cubic inch. And I would assume this becomes even less important with FI.
It's like comparing the Chevy 302 to the 305, one can be a monster and one can be a nice boat anchor.
Those are good valid points. I think I'm doing these calcs more for fun and understanding than any other reason. I definitely wouldn't spend $20K for a 350CI engine (unless it offered some advantage that made it worthwhile). If I could build the theoretical engine for $5k I would do it.
I am really interested in combining high performance and efficiency. That is why I want to Procharge my stock LS1 and build a forged LS1 when the stock one breaks. As long as you stay mostly out of boost in highway driving you will retain your 27-28 MPG.
But imagine how an 8000+ rpm LSx would sound!! All while getting better highway MPG.
Here you go 8400 rpm. Some people destroke the 6.0s and I saw a LS1 destroked as well somewhere else. It would be much cheaper to do this rather than a LSX / LS7 block.
Might want to consider an iron block as well. The LS7 in particular has a weak link in the sheaves from what i have read. I'm sure someone will chime in and give you the limits on the LS1 sleaves, I'm sure it will handle whatever you have in mind though.
Here you go 8400 rpm. Some people destroke the 6.0s and I saw a LS1 destroked as well somewhere else. It would be much cheaper to do this rather than a LSX / LS7 block.
Might want to consider an iron block as well. The LS7 in particular has a weak link in the sheaves from what i have read. I'm sure someone will chime in and give you the limits on the LS1 sleaves, I'm sure it will handle whatever you have in mind though.
Thanks man, that's a cool vid. For what I want to do, the only possible choice is a block capable of 4.125" bore. The only iron block that I know of capable of this is the LSX. With such a short stroke, the large bore is critical to the mechanical advantage and not losing low end torque in a destroked 7.0L (destroked to 5.7L).
Basically, the idea is to build an N/A 5.7L with large bore x short stroke (and eventually boost it) that has more torque/hp across the board as compared to an N/A LS1.
RHS makes an aluminum racing block capable of 4.165" bore..that's for fantasy land. You could build a crazy powerful (high and low end) high rpm screamer with that block (using a short stroke).
I'll probably end up sticking with a forged LS1 (once the stock LS1 breaks under boost).
We built this car at the old EPP shop for a customer who practiced with it on a 2.1 mile road course. It started out with a D-1SC at 740 rwhp using the stock crank, Compstar rods, Diamond pistons, Total Seal rings and Patriot Stage 2 heads, with a very mild cam and shorty emission headers for the owner to meet Illinois requirements. Several years later we built a new engine for the customer and went with an F-1C head unit. C5 Corvettes don't get a lot of airflow into the engine bay and we added many items to this car to keep the inlet air temps down as much as possible. The one thing that seemed to make the biggest difference was an engine oil cooler. Bob
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05-23-2016, 02:43 AM
Procharged LS1(or destroked LSx) vs. Stroked LSx 
