Engine mods - expected output increase?
Discussion
So, while I find the time to strip my engine, I'm planning the rebuild of my LS2.
I want n/a, cam, and reliability. I'm not really chasing numbers, more the experience. I want the noise, the shake, the extra power is a bonus.
My current spec.
LS2
Wortec headers (I think, could someone check pic to confirm)
Wortec switchable system
Sport pac to performance pac upgrade. Whatever that does! (Map?)
Apparently around 440hp now.
That's it for power mods, other stuff too 3.9 diff, ls7 clutch etc.
Anyway, if I were to rebuild with a juicy cam, ls3 heads, ls3 intake and otrcai, what could I expect? Kind of a how long is a piece of string question based on cam choice I appreciate. I have a lot to learn in that area around what is achievable and what is driveable.
I'd love it to sound like this though!
https://youtu.be/DbAK8nK0Mcc
I want n/a, cam, and reliability. I'm not really chasing numbers, more the experience. I want the noise, the shake, the extra power is a bonus.
My current spec.
LS2
Wortec headers (I think, could someone check pic to confirm)
Wortec switchable system
Sport pac to performance pac upgrade. Whatever that does! (Map?)
Apparently around 440hp now.
That's it for power mods, other stuff too 3.9 diff, ls7 clutch etc.
Anyway, if I were to rebuild with a juicy cam, ls3 heads, ls3 intake and otrcai, what could I expect? Kind of a how long is a piece of string question based on cam choice I appreciate. I have a lot to learn in that area around what is achievable and what is driveable.
I'd love it to sound like this though!
https://youtu.be/DbAK8nK0Mcc
Cam choice will be governed by what is MOT'able, not by what might be driveable.
There probably isnt really much point changing to LS3 heads just for the same of it, good cathedral port heads will work just as well, usually make more torque, and work with your existing intake . And also your existing rocker gear
Likewise unless the LS3 intake was very cheap...it probably isnt worth spending the money on vs something better.
So a lot will boil down to your budget...
But a good aftermarket intake and good set of ported heads to go with any cam would make a lot of sense.
There probably isnt really much point changing to LS3 heads just for the same of it, good cathedral port heads will work just as well, usually make more torque, and work with your existing intake . And also your existing rocker gear
Likewise unless the LS3 intake was very cheap...it probably isnt worth spending the money on vs something better.
So a lot will boil down to your budget...
But a good aftermarket intake and good set of ported heads to go with any cam would make a lot of sense.
The ls2 intake is the worst of the lot, so you do at least have the most to gain from a swap.
As stevie says, cam is limited by mot first, not drivability.
Lopey cam sound comes from overlap, and overlap means waving goodbye to legitimate MOTs
Mikey B on here has a very successful Ls3 heads/intake swap with a cam in his ls2, if he doesn't spot this I'll ping him a message on Facebook to weigh in
I believe you should expect to be able to make 500bhp NA whilst still being able to get an mot if everything works well together, others may correct me on this though.
As stevie says, cam is limited by mot first, not drivability.
Lopey cam sound comes from overlap, and overlap means waving goodbye to legitimate MOTs
Mikey B on here has a very successful Ls3 heads/intake swap with a cam in his ls2, if he doesn't spot this I'll ping him a message on Facebook to weigh in
I believe you should expect to be able to make 500bhp NA whilst still being able to get an mot if everything works well together, others may correct me on this though.
Edited by SturdyHSV on Thursday 12th July 23:26
Edited by SturdyHSV on Thursday 12th July 23:27
Generally LS3 heads are cheaper than good LS2 heads and LS3 intake cheaper than Fast or MSD.
So thats a "budget" route. Though as mentioned ultimately either way will bring similar results.
Id argue LS3 is the better route as you can use LESS cam for the same results. This is due to the larger intake valve 2.16 vs 2.0 IIRC
Something like a 222/230 is what you are looking for with good lift.
https://www.summitracing.com/int/parts/cxm-03-04-0...
So thats a "budget" route. Though as mentioned ultimately either way will bring similar results.
Id argue LS3 is the better route as you can use LESS cam for the same results. This is due to the larger intake valve 2.16 vs 2.0 IIRC
Something like a 222/230 is what you are looking for with good lift.
https://www.summitracing.com/int/parts/cxm-03-04-0...
ringram said:
Generally LS3 heads are cheaper than good LS2 heads and LS3 intake cheaper than Fast or MSD.
So thats a "budget" route. Though as mentioned ultimately either way will bring similar results.
Id argue LS3 is the better route as you can use LESS cam for the same results. This is due to the larger intake valve 2.16 vs 2.0 IIRC
Something like a 222/230 is what you are looking for with good lift.
https://www.summitracing.com/int/parts/cxm-03-04-0...
But how appropriate is that larger intake valve for a small 4" bore ?So thats a "budget" route. Though as mentioned ultimately either way will bring similar results.
Id argue LS3 is the better route as you can use LESS cam for the same results. This is due to the larger intake valve 2.16 vs 2.0 IIRC
Something like a 222/230 is what you are looking for with good lift.
https://www.summitracing.com/int/parts/cxm-03-04-0...
Difficult to say. I don't know my cam spec - so that's not much help, but it is mild. With that, a cold air intake, 1 7/8 headers and a catless 3" system, square port heads and LS3 intake (the last two as it's an L76 rather than LS) we are around 400hp at the wheels or approximately 500bhp. People have managed 60bhp from a mild cam swap and map, so that would be all I would look at in your case.
Thank you all for the responses.
Primary reason for replacing the heads would be if I'm stripping the LPG off. Of the GM heads, the LS3 seems to be the one to go for. Ported while they are off with new moving bits.
Something like this..
https://www.summitracing.com/parts/nal-88958758
Shame about the cam/MOT. Can't rely on always having a friendly tester. 500hp is a nice round number to have as a target though.
Intake again, perhaps something like this..
https://www.summitracing.com/parts/nal-12674428
I like that the parts from summit are assembled kits, and I'd be replacing all the 130k+ parts on my engine. You pay for it though.
They are expensive, but if my bottom end isn't trashed, they are within the realms of affordable.
Primary reason for replacing the heads would be if I'm stripping the LPG off. Of the GM heads, the LS3 seems to be the one to go for. Ported while they are off with new moving bits.
Something like this..
https://www.summitracing.com/parts/nal-88958758
Shame about the cam/MOT. Can't rely on always having a friendly tester. 500hp is a nice round number to have as a target though.
Intake again, perhaps something like this..
https://www.summitracing.com/parts/nal-12674428
I like that the parts from summit are assembled kits, and I'd be replacing all the 130k+ parts on my engine. You pay for it though.
They are expensive, but if my bottom end isn't trashed, they are within the realms of affordable.
Edited by marksx on Friday 13th July 07:02
Thanks for the Facebook message Sturdy 
My goals were very similar to the OPs. Although the extra power was one of the main ones. I gave myself the target of 400rwhp (500 at the flywheel) and therefore 300bhp/tonne. Because i'm a bit of a geek about it, I visited the rolling road where the mapping was to be done before any of the work started, to get a 'before' figure. This came out at 321whp.
My original plan was a cam and FAST intake. However, reading the US forums swayed me into looking at LS3 top-end swaps. The heads (and intake) flow better and in my opinion are therefore a better choice for an NA build. I was lucky that there were LS3 (well, L92) heads and intake for sale in the UK. The cam was a custom grind - 223/231 114LSA. You'll need new valve springs, lifters, intake rockers and I also went for LS3 injectors. It's also worth fitting a new cam chain. I've probably forgotten lots of parts that were fitted - it's been a few years since I put the parts list together! The following is a link to the story of the build, from start to finish:
https://www.pistonheads.com/gassing/topic.asp?h=0&...
AAS did the work and I'll still remember the day I picked it up - the idle is just
To me, it's how a muscle car should be - gently rocking on idle, loping soundtrack.
After mapping it achieved 404rwp (same dyno). I think it equated to nearly 500hp at the flywheel. It makes peak power at the rev limit, so you could tame down the cam a little, to move the power curve further down the rev range (or fit rod bolts and raise the rev limit for more power). To be honest, I don't think the numbers do the performance justice. I've done Thunder Road a few times (a standing one mile drag race) and excluding bored/stroked-engined cars, it's best in class. The last time I ran I managed 170.96mph. Put simply, in my opinion the performance is more than the sum of the parts.
Check here for the results so you can compare it to other cars: http://www.thunderroad.co/oc17/index.php?route=inf...
Feel free to ask any questions. The one piece of advice I'd give is to spend time researching - the information is out there. I spent hundreds of hours reasearching parts, matching them to other parts, basically growing a build from scratch. For example, there's little point buying a FAST for an LS3 as it's only worth a few whp. IMHO not worth it for the circa £1k it costs.
Emissions wise, unbelievably my car passes with sports cats. You have to get the cats hot, but it is a genuine pass.
Hope that helps
My goals were very similar to the OPs. Although the extra power was one of the main ones. I gave myself the target of 400rwhp (500 at the flywheel) and therefore 300bhp/tonne. Because i'm a bit of a geek about it, I visited the rolling road where the mapping was to be done before any of the work started, to get a 'before' figure. This came out at 321whp.
My original plan was a cam and FAST intake. However, reading the US forums swayed me into looking at LS3 top-end swaps. The heads (and intake) flow better and in my opinion are therefore a better choice for an NA build. I was lucky that there were LS3 (well, L92) heads and intake for sale in the UK. The cam was a custom grind - 223/231 114LSA. You'll need new valve springs, lifters, intake rockers and I also went for LS3 injectors. It's also worth fitting a new cam chain. I've probably forgotten lots of parts that were fitted - it's been a few years since I put the parts list together! The following is a link to the story of the build, from start to finish:
https://www.pistonheads.com/gassing/topic.asp?h=0&...
AAS did the work and I'll still remember the day I picked it up - the idle is just
To me, it's how a muscle car should be - gently rocking on idle, loping soundtrack.After mapping it achieved 404rwp (same dyno). I think it equated to nearly 500hp at the flywheel. It makes peak power at the rev limit, so you could tame down the cam a little, to move the power curve further down the rev range (or fit rod bolts and raise the rev limit for more power). To be honest, I don't think the numbers do the performance justice. I've done Thunder Road a few times (a standing one mile drag race) and excluding bored/stroked-engined cars, it's best in class. The last time I ran I managed 170.96mph. Put simply, in my opinion the performance is more than the sum of the parts.
Check here for the results so you can compare it to other cars: http://www.thunderroad.co/oc17/index.php?route=inf...
Feel free to ask any questions. The one piece of advice I'd give is to spend time researching - the information is out there. I spent hundreds of hours reasearching parts, matching them to other parts, basically growing a build from scratch. For example, there's little point buying a FAST for an LS3 as it's only worth a few whp. IMHO not worth it for the circa £1k it costs.
Emissions wise, unbelievably my car passes with sports cats. You have to get the cats hot, but it is a genuine pass.
Hope that helps
Edited by mikeyb1987 on Friday 13th July 11:01
If tests like this are anything to go by...the LS3 heads are of no real advantage here, in pretty much their words unless you can use a big enough cam to see the heads perform. And MOT rules will knock that on the head.
And as the cathedrals make the same power but more low rpm torque...for a daily that has to be a better option ?
http://www.superchevy.com/how-to/ghtp-1205-cathedr...
The money would probably be better spend on good cathedral heads and the intake. Yes the LS3 intake is good...but to swap to LS3 you need to buy both the rocker gear and an intake. How much does that add up to compared to a good FAST or MSD intake for the cathedrals which will offer better all round gains.
LS3 heads seem to make big flow claims but it doesnt really seem to translate to huge amounts more power against a comparable cathedral.
And as the cathedrals make the same power but more low rpm torque...for a daily that has to be a better option ?
http://www.superchevy.com/how-to/ghtp-1205-cathedr...
The money would probably be better spend on good cathedral heads and the intake. Yes the LS3 intake is good...but to swap to LS3 you need to buy both the rocker gear and an intake. How much does that add up to compared to a good FAST or MSD intake for the cathedrals which will offer better all round gains.
LS3 heads seem to make big flow claims but it doesnt really seem to translate to huge amounts more power against a comparable cathedral.
I'm fairly sure LS3 intake will mean injectors too just as a heads up. Looking on RockAuto, OEM LS3 injectors (useful as accurate flow data is available for when it's tuned) you'd be looking at about ~£30 x 8, fuel rails the LS3 part looks to also fit the LS2, so that's ~£90 saved already!
SturdyHSV said:
I'm fairly sure LS3 intake will mean injectors too just as a heads up. Looking on RockAuto, OEM LS3 injectors (useful as accurate flow data is available for when it's tuned) you'd be looking at about ~£30 x 8, fuel rails the LS3 part looks to also fit the LS2, so that's ~£90 saved already!
Yep, they will need injectors. Avoid LS9 injectors as the spray pattern isn't optimised for LS3 heads. Same fuel rails can be used.
I'd read about the injectors, that's one of the reasons I liked the one linked from summit where it is all there.
Interesting article, thanks Stevie. If there isn't that much benefit to the ls3 heads, I need to see what constitutes a 'good' cathedral head, then find associated intake. FAST or similar.
Interesting article, thanks Stevie. If there isn't that much benefit to the ls3 heads, I need to see what constitutes a 'good' cathedral head, then find associated intake. FAST or similar.
Isn't the linked article comparing ported LS2 heads? They clearly state that stock to stock, LS3 are way better. A quick search on Summit and LS2 ported heads are quite a lot more than Chevy Performance LS3 heads.
As I said in my post above, you have to match the parts you're going to be using. LS3 heads seemed to be the better option for my build
As I said in my post above, you have to match the parts you're going to be using. LS3 heads seemed to be the better option for my build
stevieturbo said:
The money would probably be better spend on good cathedral heads and the intake. Yes the LS3 intake is good...but to swap to LS3 you need to buy both the rocker gear and an intake. How much does that add up to compared to a good FAST or MSD intake for the cathedrals which will offer better all round gains.
LS3 heads seem to make big flow claims but it doesnt really seem to translate to huge amounts more power against a comparable cathedral.
I'm with Stevie on this one. You should get a better velocity through the cathedral ports due to the runner volumes and shape of the runner roof. I can recommend a 224/232/114 with 4 deg advance built in which will work with either set of heads. But I have found the same as Stevie that there is a lot of hype on the LS3/L92 head but no greater advantage in real life results bang for buck over a good set of 243's.LS3 heads seem to make big flow claims but it doesnt really seem to translate to huge amounts more power against a comparable cathedral.
If you stick with the LS2 heads (which as stevie says will mean you can use your very good stock rockers, try and find a Fast 92, port match and then port the TB for good measure. Also add to your list a really good intake filter (CAI) with large surface area (cone type). With this setup you will need a set of slighly longer push rods so allow for the cost of those. Oh and ditch the stock lifters for a set of GM Cadilac HI rpm lifters.
HTH?
Although it's a few years old, this would do no harm
https://www.amazon.co.uk/gp/product/1613254318/ref...
I bought it recently myself and it has quite a few tests in it. Mostly airflow tests as opposed to dyno/hp tests but it does cover a very wide range of heads including many ported OEM offerings.
Costwise, if you could find somewhere trustworthy and reputable in the UK who could port your own heads, that would be the cheapest option
That said, a lot of the US stuff outright sale is keenly priced.
But then....the aftermarket stuff is too. And perhaps even more so, as good as OEM LS heads are, the aftermarket stuff is just a lot better.
But for sake of £16 for the book, it will give you a lot of options to consider.
https://www.amazon.co.uk/gp/product/1613254318/ref...
I bought it recently myself and it has quite a few tests in it. Mostly airflow tests as opposed to dyno/hp tests but it does cover a very wide range of heads including many ported OEM offerings.
Costwise, if you could find somewhere trustworthy and reputable in the UK who could port your own heads, that would be the cheapest option
That said, a lot of the US stuff outright sale is keenly priced.
But then....the aftermarket stuff is too. And perhaps even more so, as good as OEM LS heads are, the aftermarket stuff is just a lot better.
But for sake of £16 for the book, it will give you a lot of options to consider.
mikeyb1987 said:
Thanks for the Facebook message Sturdy
My goals were very similar to the OPs. Although the extra power was one of the main ones. I gave myself the target of 400rwhp (500 at the flywheel) and therefore 300bhp/tonne. Because i'm a bit of a geek about it, I visited the rolling road where the mapping was to be done before any of the work started, to get a 'before' figure. This came out at 321whp.
My original plan was a cam and FAST intake. However, reading the US forums swayed me into looking at LS3 top-end swaps. The heads (and intake) flow better and in my opinion are therefore a better choice for an NA build. I was lucky that there were LS3 (well, L92) heads and intake for sale in the UK. The cam was a custom grind - 223/231 114LSA. You'll need new valve springs, lifters, intake rockers and I also went for LS3 injectors. It's also worth fitting a new cam chain. I've probably forgotten lots of parts that were fitted - it's been a few years since I put the parts list together! The following is a link to the story of the build, from start to finish:
https://www.pistonheads.com/gassing/topic.asp?h=0&...
AAS did the work and I'll still remember the day I picked it up - the idle is just To me, it's how a muscle car should be - gently rocking on idle, loping soundtrack.
After mapping it achieved 404rwp (same dyno). I think it equated to nearly 500hp at the flywheel. It makes peak power at the rev limit, so you could tame down the cam a little, to move the power curve further down the rev range (or fit rod bolts and raise the rev limit for more power). To be honest, I don't think the numbers do the performance justice. I've done Thunder Road a few times (a standing one mile drag race) and excluding bored/stroked-engined cars, it's best in class. The last time I ran I managed 170.96mph. Put simply, in my opinion the performance is more than the sum of the parts.
Check here for the results so you can compare it to other cars: http://www.thunderroad.co/oc17/index.php?route=inf...
Feel free to ask any questions. The one piece of advice I'd give is to spend time researching - the information is out there. I spent hundreds of hours reasearching parts, matching them to other parts, basically growing a build from scratch. For example, there's little point buying a FAST for an LS3 as it's only worth a few whp. IMHO not worth it for the circa £1k it costs.
Emissions wise, unbelievably my car passes with sports cats. You have to get the cats hot, but it is a genuine pass.
Hope that helps
ahhhh them was the days. My goals were very similar to the OPs. Although the extra power was one of the main ones. I gave myself the target of 400rwhp (500 at the flywheel) and therefore 300bhp/tonne. Because i'm a bit of a geek about it, I visited the rolling road where the mapping was to be done before any of the work started, to get a 'before' figure. This came out at 321whp.
My original plan was a cam and FAST intake. However, reading the US forums swayed me into looking at LS3 top-end swaps. The heads (and intake) flow better and in my opinion are therefore a better choice for an NA build. I was lucky that there were LS3 (well, L92) heads and intake for sale in the UK. The cam was a custom grind - 223/231 114LSA. You'll need new valve springs, lifters, intake rockers and I also went for LS3 injectors. It's also worth fitting a new cam chain. I've probably forgotten lots of parts that were fitted - it's been a few years since I put the parts list together! The following is a link to the story of the build, from start to finish:
https://www.pistonheads.com/gassing/topic.asp?h=0&...
AAS did the work and I'll still remember the day I picked it up - the idle is just
To me, it's how a muscle car should be - gently rocking on idle, loping soundtrack.After mapping it achieved 404rwp (same dyno). I think it equated to nearly 500hp at the flywheel. It makes peak power at the rev limit, so you could tame down the cam a little, to move the power curve further down the rev range (or fit rod bolts and raise the rev limit for more power). To be honest, I don't think the numbers do the performance justice. I've done Thunder Road a few times (a standing one mile drag race) and excluding bored/stroked-engined cars, it's best in class. The last time I ran I managed 170.96mph. Put simply, in my opinion the performance is more than the sum of the parts.
Check here for the results so you can compare it to other cars: http://www.thunderroad.co/oc17/index.php?route=inf...
Feel free to ask any questions. The one piece of advice I'd give is to spend time researching - the information is out there. I spent hundreds of hours reasearching parts, matching them to other parts, basically growing a build from scratch. For example, there's little point buying a FAST for an LS3 as it's only worth a few whp. IMHO not worth it for the circa £1k it costs.
Emissions wise, unbelievably my car passes with sports cats. You have to get the cats hot, but it is a genuine pass.
Hope that helps
Edited by mikeyb1987 on Friday 13th July 11:01
I did the same sort of. I had a CV8 5.7 target was 500FWHP and 400RWHP but it was more the noise I wanted and rumble of the V8 but with a few bits like Mike above I got 504FWHP and 419RWHP. long time ago now I did thid and have sold the car.
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