LS swap questions

[LowchevyII]

So im looking to do an LS swap in my 70 nova and have a few questions for the many knowledgeable gurus around here.

-thinking of going with an LQ4 (to keep costs down) with L92 heads. What intake and throttle body should i use?
-What cam should i go with to make between 500-550 horse at the crank?
-Hope to be running a t-56 tranny.
-what fuel rails and injectors?
-finally what all do i need in terms of wiring harness and ecu for this all to work?
- also, anything else i may be forgetting
Any advice and/or suggestions would be amazing.

thanks in advance guys,

Jeff

[Mkelcy]

My advice and suggestion would be to search here and at LS1tech.com and Pro-Touring.com. There's a ton of information available.

[69MyWay]

So im looking to do an LS swap in my 70 nova and have a few questions for the many knowledgeable gurus around here.

-thinking of going with an LQ4 (to keep costs down) with L92 heads. What intake and throttle body should i use?
-What cam should i go with to make between 500-550 horse at the crank?
-Hope to be running a t-56 tranny.
-what fuel rails and injectors?
-finally what all do i need in terms of wiring harness and ecu for this all to work?
- also, anything else i may be forgetting
Any advice and/or suggestions would be amazing.

thanks in advance guys,

Jeff

-thinking of going with an LQ4 (to keep costs down) with L92 heads. What intake and throttle body should i use?

**Depends on if you are going with drive by wire or cable. I vote for dbw. If so...you can get the truck motor, than a LS1/6 Corvette intake and you can still use the dbw TB that may have come on the truck donor.

-What cam should i go with to make between 500-550 horse at the crank?

**I would contact Comp Cam - discuss your gear ratio - transmission, and expectations.

-Hope to be running a t-56 tranny.

**This would make it wise to buy a LS donor that comes with the transmission because piecing it all together is a real pain and can get more expensive than just having bought a LS1/2 with T56 from day one.

-what fuel rails and injectors?

**Stock rails are fine - but that kind of hp will you will want some 35# or so injectors. SLP can also set you up with a cam and injectors together.

-finally what all do i need in terms of wiring harness and ecu for this all to work?

**I suggest you get a painless harness - and run on a 0411 PCM (especially if you go dbw)

Oh...if you go DBW, you will need the pedal and TAC module out of the donor - unless it is a 2006 - up LS with a 52 tooth wheel and the newer computer.

Confused yet? LS1tech has great info about this swap as well.

[LowchevyII]

ok so heres what i am thinking. Carcraft did a build up on this thing basically.

http://www.carcraft.com/techarticles/ccrp_0705_chevrolet_ls2_l92_cylinder_heads/index.html

my only thing is that i want to go fuel injected, i dont think i want to go the carb route that they went so im thinking going with the

-F.A.S.T LSXr 102mm intake
-the 102mm tb with throttle positioning sensor (does this mean its drive by wire with that?)
-fast fuel rails
-35-37# injectors

-l92 heads

this is the cam they used in the artice
XFI™, XR281HR13
Street/Strip, High RPM, Works well with FAST™ Intake

so what would be suitable valve springs for this cam?

is this a decent combo or what would you guys change/suggest otherwise


thanks again guys

[70rs]

Regardless of what cam you select, get with that cams manufacturer to find out what valve springs you should run with it.

And regarding the post above and the LS1/LS6 intake with the L92 heads (good intakes) I think the L92 heads have a different intake port design than the LS1/6 does. It is more like the LS7 ports (rectangle?)if I remember correctly. But please don't take my word for it, just double check. :cheers:

[ivmotor]

Regardless of what cam you select, get with that cams manufacturer to find out what valve springs you should run with it.

And regarding the post above and the LS1/LS6 intake with the L92 heads (good intakes) I think the L92 heads have a different intake port design than the LS1/6 does. It is more like the LS7 ports (rectangle?)if I remember correctly. But please don't take my word for it, just double check. :cheers:


Definitely different port configs between ls1,6,2 (cathedral) and ls3, l76, l92 (rectangle) and ls7 (huge rectangle with higher bolt pattern). The l76 and ls3 intakes will make all the power you'll need, I think they can be bought for $350-400.

Howe makes better harnesses than painless. I do a bunch of conversions and have had numerous painless failures due to pin fit in the connectors.

The oem computers are fantastic, very tunable and reliable.

[LowchevyII]

good info guys, keep it coming. Thanks for the heads up on teh intakes. As nice as that FAST unit is, i just dont think i can swing 1000 for the intake, 550 for the TB and 200 for the fuel rails. Glad i can probably get a LS3 intake for about 500 tops that will work sufficiently

[69MyWay]

Definitely different port configs between ls1,6,2 (cathedral) and ls3, l76, l92 (rectangle) and ls7 (huge rectangle with higher bolt pattern). The l76 and ls3 intakes will make all the power you'll need, I think they can be bought for $350-400.

Howe makes better harnesses than painless. I do a bunch of conversions and have had numerous painless failures due to pin fit in the connectors.

The oem computers are fantastic, very tunable and reliable.

I'd like hear more details about the pin issue - and how recent/old has this problem been. They now have a high dollar machine that every EFI harness goes in for a full go/no-go electrical test unlike anything else out there. Perhaps as a result of failures...or just trying to prevent them.

I have run Howe products with success as well as currentperformance and others. Been fortunate to have good luck with all of them...but remembering at the same time...there's no such thing as bolt on...when hot rodding! LOL!

[ivmotor]

I do mostly sand rails and rock crawlers so they might be more severe use...

painless #60217 round trans plug 2-3 solenoid wire no continuity. Found insulation not sufficiently removed from wire before crimped. 3 years ago

painless #60520 bank 1 coil pack intermittent main power. Found loose crimp. 2.5 years ago

painless #60217 bank 2 coil pack intermittent #6 spark. Found plastic flashing keeping pin from locking into connector. 2 years ago.

None of these were faulty out of the box, they took time to show problems. The later two were a bitch to find and were worsened by vibration and heat, but the poor crimp quality is what caused the failure.

I haven't had an issue with Howe, but I've only used them for 2 years. The painless in my car hasn't had problems either.

[Z06vette]

If you get the factory engine harness with your donor, you can have it sent out to be reworked. I had speartech do mine, nice quality work from what I can see on mine. A local guy did a 5.3 motor in that body style nova with a cowl hood, and all the truck accessories/intake fit under the hood- barely. I am not sure what motor mount setup was used or if he made them himself to gain some clearance. A 6.0 would be the same fit ;) A nice cam, long tube headers, and a good tune should get you close to 500 crank HP. Keep us updated on your project!
Scott

[LowchevyII]

definitely, i just want to thank all of you guys for the info. I will keep you up on the project as best as i can. Once i sell my 350/350 combo ill have some cash and am hopefully soon to come up on a new job so i can start floating some more cash toward the nova. I really cant wait and this is all stuff ive been wanting to do for so long i cant wait to start, as well and show you guys my progress. As i progress, i hope to get some more insight and advice. this site has been so great to me. i hope to give back soon.

thanks again guys,

jeff

ps

if you know anyone with an lq4/9 shortblock for sale or a complete lq4 (for a decent price) let me know :cheers:

[IndyNova]

there is a guy in southern indiana that has some lq9's for sale, i'll see if I can 't find his number. Also, I would check out the truck sites that had those motors in them, silveradoss.com, etc. sometimes they have them in the for sale section. good luck, i'll be doing this swap also

[1970camaroRS]

Just wanted for you to keep in mind that with a .041 compressed gasket your LQ4/L92 head combo will have 9.4:1 compression. With a .051 gasket it will be 9.2:1. Give or take .1

You'll have to keep the cam a bit on the small side for duration in order to keep it from being a dog down low.

If you look at the dyno graph of the engine built by CarCraft, when they went from the stock LQ4 heads to the L92 heads they actually lost a good bit of power from 2,200 rpm to 4,800 rpm with the largest loss of -21 ft/lbs at 2,200 rpm and -10 to -16 in the mid-range. Of course, after 5,000rpm when those big (260+cc) heads got into their grove they handed the stock heads....well, their heads. Also, the Hot Cam used in the CarCraft motor is JUNK when compared to other modern grinds for LSx engines. Try a G6x92-3 L92 specific cam or something similar. But only do so after you mill the heads down to about 64cc or less to bring compression up over 10:1. Also, invest in some ARP rod bolts if you're going to spin it to 6,800rpm like CarCraft did.

[LowchevyII]

Just wanted for you to keep in mind that with a .041 compressed gasket your LQ4/L92 head combo will have 9.4:1 compression. With a .051 gasket it will be 9.2:1. Give or take .1

You'll have to keep the cam a bit on the small side for duration in order to keep it from being a dog down low.

If you look at the dyno graph of the engine built by CarCraft, when they went from the stock LQ4 heads to the L92 heads they actually lost a good bit of power from 2,200 rpm to 4,800 rpm with the largest loss of -21 ft/lbs at 2,200 rpm and -10 to -16 in the mid-range. Of course, after 5,000rpm when those big (260+cc) heads got into their grove they handed the stock heads....well, their heads. Also, the Hot Cam used in the CarCraft motor is JUNK when compared to other modern grinds for LSx engines. Try a G6x92-3 L92 specific cam or something similar. But only do so after you mill the heads down to about 64cc or less to bring compression up over 10:1. Also, invest in some ARP rod bolts if you're going to spin it to 6,800rpm like CarCraft did.

hadnt been on this post in a while but i just noticed your response. thanks for the heads up on this. ill definitely keep this stuff in mind.