408 stroker with twins
01-31-2014, 05:19 PM
#41
Sure the technology is a huge part of it and as you saw, compressor to turbine ratio which is pretty much ideal on a 3582R and very nice on the 6266 as well.
A lot of this stuff doesn't have enough turbine wheel which is why I hate the TC series. TC76 has slower response than the same turbo with a 75mm turbine as it just doesn't have enough torque to drive the compressor.
And again, a lot of this just comes down to preference. Some guys like huge choppy cams and the huge hit of a laggy turbo. I personally like super fast low rpm response and a smooth idle.
I think it's hard for many to make these decisions because they may have never even driven a turbo LSX car and some of the characteristics are hard to explain unless you have driven many different combos.
A lot of this stuff doesn't have enough turbine wheel which is why I hate the TC series. TC76 has slower response than the same turbo with a 75mm turbine as it just doesn't have enough torque to drive the compressor.
And again, a lot of this just comes down to preference. Some guys like huge choppy cams and the huge hit of a laggy turbo. I personally like super fast low rpm response and a smooth idle.
I think it's hard for many to make these decisions because they may have never even driven a turbo LSX car and some of the characteristics are hard to explain unless you have driven many different combos.
theyre 66/65's) 
02-02-2014, 12:28 PM
#46
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Glad I found this thread. Hope it's not too much of a hijack, but how about your thoughts on my combo?
lq4 block, .030 over, 05 model year
lsa heads with the intake wing deleted
Holley high ram
Oliver billet rods
Probably Wiseco pistons, 9.5:1 ish
Custom turbo cam, been talking to Lil John
Twin GT3582r turbos, Tial stainless v-band 1.03 housings
Custom tube headers, 3 or 3.5" exhaust
ARP head and main studs
ATI damper
93 octane, as e85 is hard to find here
411 computer, 96 or 120 injectors, twin 255 walbros
I have everything listed but the pistons and injectors, trying to decide if I should do the 4" stroke crank or keep it 370 cu.in.
John seems to feel the 4" stroke is too much for the turbos, but this and some other reading has me thinking it isn't such a bad idea. Bigger turbos later would certainly be easier than wishing it had more displacement and therefore pushing 30 lbs in the intake trying for numbers. I would love to keep the rpm down, and therefore keep the valvetrain happier. Making good boost by 3-3500 would be nice as opposed to buzzing it 5000 to get it to light. Then limit rpm to keep backpressure in check??? Thoughts?
lq4 block, .030 over, 05 model year
lsa heads with the intake wing deleted
Holley high ram
Oliver billet rods
Probably Wiseco pistons, 9.5:1 ish
Custom turbo cam, been talking to Lil John
Twin GT3582r turbos, Tial stainless v-band 1.03 housings
Custom tube headers, 3 or 3.5" exhaust
ARP head and main studs
ATI damper
93 octane, as e85 is hard to find here
411 computer, 96 or 120 injectors, twin 255 walbros
I have everything listed but the pistons and injectors, trying to decide if I should do the 4" stroke crank or keep it 370 cu.in.
John seems to feel the 4" stroke is too much for the turbos, but this and some other reading has me thinking it isn't such a bad idea. Bigger turbos later would certainly be easier than wishing it had more displacement and therefore pushing 30 lbs in the intake trying for numbers. I would love to keep the rpm down, and therefore keep the valvetrain happier. Making good boost by 3-3500 would be nice as opposed to buzzing it 5000 to get it to light. Then limit rpm to keep backpressure in check??? Thoughts?
02-12-2014, 04:27 PM
#48
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Chris,the Typhoon your speaking of is mine,it has already gone 149 like INTMD8 posted and has ET'd 9.50's.In my opinion it is the perfect compromise of HP and lag,the 2nd of which is almost non existent.At 10.5 psi it makes 799hp on 93 octane turned up,not maxed out just turned up to 18psi it made just shy of 1k hp,to me it I couldn't be happier.Although they are a relatively small impeller size they make very good power through out the RPM range and as proven have the ability to make great over-all numbers.I am in total agreement with you on the turbo sizing,there is no reason if your goals are near the 1k level to run anything larger,that is unless your goals are to have a laggy POS
09-29-2018, 10:02 AM
#49
Bump! Lots of good info in this thread. Can someone point me in the direction of a setup that isn’t laggy on the street on pump gas with around 800hp through a 4L80E with the AC blowing nice and cold that can run mid 8’s when at the track in a 3800 lb 4th gen? These discussions on factory blocks @ 1000 hp on meth/race gas are interesting, but I‘ll need more than that to hit my goals in this heavy *** car. Is a re-sleeved 427 IV gen block with twin 6262’s the answer to my needs? Who’s running this or similar setups in their heavy 4th gen F-body? Point me to those build threads please. I know there’s many variables here and I’ll be knocked for lack of weight reduction, just wondering what’s out there.
I read conflicting information about heads lifting if they are only 4 bolt, the need to go 6 bolt at 1200 rwhp....4 inch stroke with 4.125 bore not being good for boost....don't use anything but a dragon slayer at 1200 rwhp...don't even try it without an lsx or dart iron block...just use a 370 with twins and save money...ask 4 people get 4 different opinions...lol....just trying to make sense of it all and base the decision on actual builds and experiences from those who have those builds rather than re-hashed opinions that aren't based on actual data. I am a proponent of the better safe than sorry idea over saving a few bills and I'll like to be directed to those who have builds that have already accomplished what I'd like to do.
I read conflicting information about heads lifting if they are only 4 bolt, the need to go 6 bolt at 1200 rwhp....4 inch stroke with 4.125 bore not being good for boost....don't use anything but a dragon slayer at 1200 rwhp...don't even try it without an lsx or dart iron block...just use a 370 with twins and save money...ask 4 people get 4 different opinions...lol....just trying to make sense of it all and base the decision on actual builds and experiences from those who have those builds rather than re-hashed opinions that aren't based on actual data. I am a proponent of the better safe than sorry idea over saving a few bills and I'll like to be directed to those who have builds that have already accomplished what I'd like to do.
Last edited by 5.7stroker; 09-29-2018 at 10:17 AM.
09-29-2018, 11:56 AM
#50
9 Second Club
You sure as hell arent going to run mid 8's at 800hp and 3800lbs no matter what block you use. And I doubt a pair of 6262's will get you there either at that weight unless everything else is perfect.
09-29-2018, 12:08 PM
#51
Certainly not which is why the question is can a 427 with 6262's get you there with everything perfect? If not, what combo will get you there that can be tuned down to 800 hp on the street without being a laggy POS, while also still being able to go all out on the track with more boost and race gas for more power?
09-29-2018, 12:31 PM
#53
9 Second Club
Certainly not which is why the question is can a 427 with 6262's get you there with everything perfect? If not, what combo will get you there that can be tuned down to 800 hp on the street without being a laggy POS, while also still being able to go all out on the track with more boost and race gas for more power?
I'd struggle to see how most turbo setups could be laggy given the nature of an auto....when will you ever see high throttle openings at low rpm in order for there to be lag ?
Certainly a larger engine will always make power more easily than a smaller...so assuming you can get the block built correctly, it would be hard to find downsides
09-29-2018, 12:33 PM
#54
Everyone is fully aware that weight savings makes hitting lower ET's easier. I'm however interested in how much power it will take to do it at the higher weight while not being a laggy POS on the street when lowering the boost such that it isn't enjoyable on the street. I'm not interested in gutting the car. I'll remove what I can and replace with lower weight parts and still have it street able, sure.
09-29-2018, 12:37 PM
#55
I would deem 6262's very small for a 427.
I'd struggle to see how most turbo setups could be laggy given the nature of an auto....when will you ever see high throttle openings at low rpm in order for there to be lag ?
Certainly a larger engine will always make power more easily than a smaller...so assuming you can get the block built correctly, it would be hard to find downsides
I'd struggle to see how most turbo setups could be laggy given the nature of an auto....when will you ever see high throttle openings at low rpm in order for there to be lag ?
Certainly a larger engine will always make power more easily than a smaller...so assuming you can get the block built correctly, it would be hard to find downsides
09-29-2018, 01:17 PM
#57
So what I'm thinking is that a 427 with twin 6767's on high enough boost will put out enough power at the track to hit the 8.5 ET goal, and then I can tune it down to around 800HP so that it's streetable, yet still responsive at that power level with very minimal lag. Since it's an auto with twins, it sounds like the lag won't be bad at all at the lower boost 800 hp level if the right converter is used. I'm trying to avoid building 2 cars here even though there's definitely compromise.
Looking for info on who's running 427 aluminum re-sleeved twin turbo "street car" setups and what track times they are running at what weight.
Last edited by 5.7stroker; 09-29-2018 at 01:26 PM.
09-29-2018, 04:49 PM
#58
I gotcha. I would look at what guys like mighty mouse, cablebandit, there was another guy running a gt55 with a 408 that was a real street car and would walk liter bikes. I don't think you need a 427 and would be better suited to keep the cylinder walls as thick as possible. Like you said, 6 bolt is good insurance for when you turn it up.
10-02-2018, 04:21 PM
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I gotcha. I would look at what guys like mighty mouse, cablebandit, there was another guy running a gt55 with a 408 that was a real street car and would walk liter bikes. I don't think you need a 427 and would be better suited to keep the cylinder walls as thick as possible. Like you said, 6 bolt is good insurance for when you turn it up.
they have a thicker deck. ls9 gaskets, bottom end and top end studs. This is a strong enough combo for a long life without breaking the bank.
I have all these pieces or a complete short block should you decide you don't need to blow 10k I have a complete turbo engine that with those 160 lb injectors will put out that kind of hp with t04 t60 turbos ready to go for 5500
see if you can beat that hp to dollar ratio pm me if interested