UOP

Been registered a while but this is my first post, since I mainly registered for research purposes and don't currently own a LS powered vehicle. If things go right, that will change within the next month or two. That said, I was wondering if you guys would be kind enough to take a look at my potential combo to see if it will meet my goal of having a low maintenance, daily driveable, car that will run 11.00 or quicker 1/4 mile times.

Current combo:
1986 Mazda RX7
2950 lbs
Small block Mopar (mild carb'd 5.9 from a Dakota R/T, approx 280-300 whp)
2004r
3600 stall
IRS 8.8, 3.73
26" tire
Best 1/4: 11.87 @ 113, 1.58

For what it is the car runs good and I can hop in it and drive anywhere, but by comparison is slow compared to LS swapped RX7's so I know there is room for improvement.


So after a ton of research, including built 5.3's and such, I've pretty much settled on picking up a low mileage LY6 and building on that.

Basic plan so far:
08 LY6 (Current offerings are ~100k miles)
ASA cam w/ PAC 1218 springs (From my research there are better cams, but supposedly it works ok with the L92 heads. Besides, the kit is practically being given to me by a buddy who is more than happy to persuade me to move to the dark side, so it will at least get me going.)
Edelbrock Victor Jr L92 intake
Holley 850 dp
1 3/4" longtubes

Anything else you guys would like to add? I'd like to not pull the heads if I don't have to, but since the front cover needs to come off to install the VVT delete kit I will replace the oil pump while I'm at it. Stock replacement GM pump ok? With only .525" lift, should the stock lifters and pushrods be ok?

As for the rest of the combo, I'm not against sending my converter to be loosened up a bit. I just rebuilt my carrier with new gears so for the time being I'm going to stick with the 3.73's.

I hope that is enough to get this started but if I missed anything please let me know. Your help is very much appreciated.

Thanks

ZONES89RS

iTrader: (25)

Surely you should get a custom grind cam that will get the most from the engine. You will wish you did.

My buddy has that body style rx7 and it weighs 2400 lbs from what he tells me.

Prorac1

iTrader: (4)

I agree with the custom cam as well. I also have an LY6 swap and went with a custom cam. The rectangular port heads are very fussy when it comes to cam selection. Don't get me wrong, they will work good with any cam, but the difference between the guys running quick, and the guys running PSYCOTICLY QUICK is the cam. Its all in what you want out of the combo. Eric L

fast89stang

iTrader: (2)

custom cam ly6 here with l92 heads. Times in sig. Be hard for a rx7 not to fly with this combo. Makes roughly 580-600 in my car. Oh, I ran 10.3s when carb was bad, should see 9s now.

BigEd_72455

iTrader: (7)

I can appreciate the desire for a 6.0, but don't discount a well built 5.3. Seriously. Mine is BONE stock except for being carb'd and this sucker FLIES in my S-10. I don't really push it that hard either... I go to 5900, grab a gear and keep on trucking (literally)..

Not to mention they are cheaper to get ahold of by several hundred dollars most of the time.

Even the 4.8's do well with a set of 799's and a good cam, just look at zones89RS S-10 extended cab project he built.

Do a bit more research on the smaller motors and you will find that they are not that far behind what the larger motors are doing with the same upgrades.

speedtigger

iTrader: (16)

The appeal of the 6 liter engine is the ability to run the square port heads. It is a great budget option. Another budget option is the use of the CNC ported cathedral port heads. I guess it all depends on how good of a deal one can find a square port engine for. If you can pick one of those off for under $1500, you just can't beat the performance per dollar.

TXsilverado

iTrader: (18)

dollar for dollar, the larger cube motors are well worth the extra money.

i swapped a bone stock 5.3 to a bone stock 5.7 LS1. no other changes. stock cams with the truck intake and full bolt ons. it dropped from a 13.88 glory pass to a consistant 13.26 in a 4,500+ lb extended cab silverado.with a cam and budget heads it went 12.19...at that weight, a 5.3 is doing good to reach 13.0 with heads/cam and the same bolt ons.

compare how many N/A 5.3 engines you see hit that magical N/A 400rwhp mark VS the 5.7 and 6.0...5.7 and 6.0 have several running 500+rwhp when a 5.3 seems to run out of steem around 385ish. 400RWHP is just a cam and boltons where a 5.3 doesnt make it often even with fully ported heads.

BigEd_72455

iTrader: (7)

I agree with you both, IF YOU HAVE THE MONEY........

Not everyone on here can afford to drop a large sum of cash ($1000-2000) for a starter build. I am thrilled with my 5.3 and feel it has a LOT of potential left with a couple minor upgrades, not even going inside except to switch the cam. Until this thing pops, the cam is all I plan to change for internals (inside the block itself).

I will say this to the OP, best of luck with your build and keep us posted on the upgrades and parts you pick up along the way. As you can tell, there is a diverse group of folks on here with several avenues available to help with reaching your goal.

But ultimately, it is your engine, your vehicle, and your bank account that dictates the path this takes. Choose with all available knowledge and options in mind, and you should not be disappointed at all... I know I wasn't.

UOP

Thanks guys, I REALLY appreciate the input.

I've read pretty much every thread based on camming a 6.0 with L92 heads here, and on Yellowbullet, and based on that I figured the GM ASA cam wasn't a super strong performer for this engine. The thing that makes it attractive to me is that it's available from a buddy for $250 with springs, and that would at least get me going. It seems to do fairly well in the LS-376 crate engine, but in the end I do plan on going the custom cam route.

That $250 is looking even better now since I went to look at an 08 LY6 and wound up buying an 09 L76 with 70k miles for $2000, puting me $500 over my original budget for the initial engine purchase.

I do have a high mileage LM7 available for free but once I took into account going into the bottom end to freshen it up (possibly add 4.8 pistons for a compression bump), and head work, I was already in the range of buying a decent L92 headed 6.0. That is what turned me away fom that build, though I know it's also a stout platform to build on.

This whole build is a last minute thing that I didn't expect to do until registration for Drag Week came around, so now I'm hustling to get this new combo together so I can be competetive in the Daily Driver class. I figure the bump spot for the 32 car field will be under 11.50 this hear (129 entries) and my current combo won't run that on motor. Granted it's been 10.89 on a 125 shot but I don't want to bracket race with nitrous. I find it hard to race the stripe when spraying.

Anyway, again, thanks for the input. I'll definitely be updating this thread as I go along. It should go fairly quickly since I want the motor ready to drop in after June 8th, which is the last race of the spring season (one of the series I run takes a break during the hot months).

Doug G

LY6 "clone" I guess you could call it ?
But the cam I have required a fly-cutting....maybe due to the shaved heads ?

Would I consider it a DD ? Not really, but then 20 years ago would have been a different story

ZONES89RS

iTrader: (25)

If I can find a combination of valve springs and everything to support a l92 or ls3 headed 6 liter that has pistons and rods forged and go 7800 rpm all day, it's going down.

That will punk my current engine and be able to take a 250 hit over the head and not think twice. There will be hurt feeling locally, and I would lol all day. That combination will do some damage without effort with supporting intake,cam and carb.

Stock, they already swing hard.

As for big ed, the difference between the 5.3 and the larger motors.....man, that 4" bore makes torque and pulls in high gear in a way that a 5.3 just cannot duplicate. My TA is fun with the cammed 5.3 that went 7.7 at 92 mph, but it's surely something you can feel on the butt dyno when the torque falls off from the lesser cubes and the 6 liter keeps pulling like a horse with his tail set on fire.

BigEd_72455

iTrader: (7)

I know the old saying "there is no replacement for displacement" but dammit these little engines run good..

I NEVER would have guessed that I would pick up 8 tenths of a second by simply changing from EFI to carb... NEVER.. Not to mention that the response of this thing now is just phenomenal!!

Doug G

Ed, I bet that old EFI intake was pretty restrictive too.

Even the GMPP motors are rated higher with a carb Vs. EFI.....hhhhmmmm

speedtigger

iTrader: (16)

If you ever look at back to back dynos where a FAST 92 or 102 is up against a Victor type single plane intake on a stock displacement sub 7000 RPM engine, you will see that the FAST long runner plastic intake kick the hell out of the single plane in average horsepower.

Now some will argue that a custom camshaft will fix all that, but I strongly disagree. A custom camshaft can help get some back, but for the circumstances described above, a short runner single plane intake will NEVER work as well as a tuned long runner intake.

In addition to the dyno data, there is a guy on Yellow Bullet who did an intake manifold swap test at the track with a Victor Jr, FAST and a Holley Hi-Ram. The FAST ran the best ET and MPH, the Holley Hi-Ram was second and the Victor Jr. was bringing up the rear. The Victor was 2-3 tenths slower in the 1/4. His combo was an LQ4, 230s @ .050" cam, 4000 converter in a 66 or 67 Chevelle set up for drag racing.

BigEd_72455

iTrader: (7)

I would think one of the main reasons would be the ability to run a much higher timing curve, which allows a significant leap in torque and horsepower.

TXsilverado

iTrader: (18)

i dont know...every 110LSA cam i've seen on a truck manifold never impressed me, but my 110LSA cam with my vic seems do good....ofcourse, i've never felt an EFI car have the throttle response of a carb so that may have something to do with the SOTP feeling.

now lets throw a nice 250 shot on each intake manifold and see which one does better

it all depends on the build. mine is a street truck geared towards the track. I dont care about average power. and i dont care how much power i have at part throttle (it still does great). all i care about is WOT from 4500-6,000 for about 3 seconds (if that), then the rest of it is all between 6,300-7,200 the entire time.

VLS1

This may be the case where A) Most are running a compromised ICL because even with fly-cut factory pistons you mostly likely still won't get ideal valve events like you could when using a custom piston and B) These are also most likely guys who are testing a carburetor intake but still using EFI with a 4150 throttle-body on top, which is less than ideal when a carburetor will atomize more consistently across all cylinders with this style of intake.

Prorac1

iTrader: (4)

For what its worth, with flycuts, im running a 105.5 ICL on my cam. Eric L

TXsilverado

iTrader: (18)

i had to flycut to fit my 236/242 110+4 cam in my LS2 with TFS heads.

VLS1

This is checked with a degree wheel I take it being 105.5? How much duration are you running with that cam?