BrownBoy

iTrader: (10)

Alright, so let’s get right down to it!

I’m putting an LM7/T-56 into my FD RX-7, my intro thread can be found here. I’ve been trying to learn as much as I can in the past few months about the LS engines and I’d like your opinions on a few of the following questions. Here is what I’m looking for:

• 375-400 whp
• Reliable as a daily driver for a few months out of the year
• Decent gas mileage, must run on pump gas
• Low end torque > top end. It’ll be a DD so I don’t need my peak torque to be at 6,000 RPM where I’ll never use it!
• Nothing too pricey, this is supposed to be a budget build.

Here is what I need some help with:

1. Fueling: I have the LS1 intake. Which fuel rails and what size injectors should I use?
2. Cam: What size? Duration? Also, which springs to support the cam you suggest?
3. Heads: I’ve got stock 862s right now (61.15cc and 9.5:1 CR). Should I keep them stock, port them, or look for something else? Stock or aftermarket valves?
4. Block: To bore or not to bore? Stock bore is 3.779in. Stock stroke 3.622in. Also, which pistons and rods to use?
5. Other: Any other things I should consider?

I know I’m asking a lot from you guys, I would greatly appreciate any help you can offer me!

Thanks!






Disclaimer: I have searched extensively for answers but couldn’t find a good package tailored for my goals so I decided to make my own thread.

conan

iTrader: (5)

What is your budget? Hard to answer the head and block question with out the $$$.

BrownBoy

iTrader: (10)

I don't have a set number in mind. I'm not going to say "I'm not spending a penny over $5,000" but I'd like to keep the cost as low as possible without cutting any corners. I want things to be done right without spending $10k on a rebuild.

What is the most cost effective way of achieveing all of my goals?

conan

iTrader: (5)

For the heads I would look in to a worked set, and for the price it's hard to beat.
Heads, http://www.texas-speed.com/shop/item...id=84&catid=20

For the block you could punch it out to a 3.898 bore and have a 346ci and use some forged pistons/rods.

Rods, http://www.texas-speed.com/shop/item...d=103&catid=39

Pistons, http://www.texas-speed.com/shop/item...d=119&catid=38

That all depends on the money you want to spend. ^^^

You don't need the extra CI to hit your goar because of the lighter car, but it will help. You can use a stock ls1 fuel rail and some 42# injectors will be plenty. Also if you can pick up a cheap ls6 intake that would help a 5.3L or a 5.7L if you go that road. The ls1 will work but the ls6 is better. Cam choice is going to depend on if you stay stock ci or go bigger.

Other things... Arp head studs, MLS head gaskets, Ported ls6 oil pump, LS2 timing chain, LS7, lifters and new trays. Also if you do go with the forged rods/pistons you could add some go gas to the mix later and nnot have to worry about the moter at all. Either way you go (5.3 or 5.7 L) you can reuse the stock crank.

BrownBoy

iTrader: (10)

Thanks for you input but I do have a bit of a rebuttal...

Worked heads, bored block, forged pistons/rods, 42# injectors, ls6 intake, and a cam? I have a feeling that will overshoot my goal and I'm pretty sure that the power I'm looking for could be achieved for much less cost.

Dabom75

iTrader: (3)

Put a 100 shot spray and get your goals when needed but then you will have DD ability too.

Someone else may can chime in on what you would need to do that cause I am dumb when it comes to spray.

conan

iTrader: (5)

I made 392rwhp/386rwtq through a t56 with a 224/563 cam, ls6 intake, and a full exhaust in a ls1. My car weighs 3,600 pounds, your car is lighter but you will need a nice head/cam on the 5.3L to hit your goal of 400rwhp.

What is the weight of your car?

Transamthunder

http://www.superchevy.com/technical/...age/index.html

Just one build i found that might be worth considering if you wanna stay close to the size your at now.

v8envy

iTrader: (1)

I have an L33 very similar engine, I have 799 heads ported, ls6 intake, tr224 cam 112 LSA JTR long tubes, 28.8 injectors, and stock ported throttle body and you are there. This is good for high 11's in our FD chassis! Add 125 shot and you can hit 10's with slicks but you just broke your diff, time to upgrade to a Cobra 8.8 call samberg rod and custom he makes amazing diff cradles

BrownBoy

iTrader: (10)

My car will weigh about 3,000 lbs.

Thanks man, Ive definitely read through that one a couple times.

That's very close to what I'm thinking of for my build. What did you put down on the dyno? I'll be staying away from spray and slicks for now to keep the rear diff happy for a while.

The only place I'm really not sure about what to do is the heads. Here is the first draft of my build:

Fueling: LS1 intake, rails and 28# injectors.

Cam: Mid-High 220's cam, somewhere in the 224-228-ish range.

Heads: This one is up for debate...Ported stock heads + valve job or new valves OR LS1 heads?

Block: Stock bore. Flat-top pistons and supporting rods. Stock bottom end.

Other: Longtubes for sure, I'm undecided on the rest. Either a Y-pipe into my existing Racing Beat or true duals with an X-pipe.

Now about those heads, does anyone know the dish volume on the 5.3 pistons compared to the 4.8 flat-tops? The main decision I need to make is whether I can go up to the LS1 heads and still have enough compression or if I'm better off just porting my 863 heads.

1fastkingcab

Well all I can tell you is that in an FD you don't need to go overboard with an LS build, there is a guy here that's local to me that had a basicly stock LS1 &T56 in his FD through the stock FD rear grear and with 275/40 ET streets and a 150 shot he was running LOW LOW 11's (like 11.1-11.2) @ around 125 MPH in the 1/4 and it was a daily driver. I belive he used an Fbody ORY and single 3" FD HKS cat back the stock FD suspenson was good for 1.45-1.50 60tf

Last I heard he did LS6 heads, Cam and changed up the exhaust. I never heard how he did after that.



Oh and you should most likely be looking at ported 5.3 heads, like conan posted a link to they will keep your C/R up where you want it. and flow like LS6 heads.

BrownBoy

iTrader: (10)

Thanks for the info but that really has nothing to do with my thread...

Do you know what my CR would be with LS1 heads? To find this out, I need to know how much the 5.3 pistons are dished compared to the 4.8s.

If it won't be high enough, I'll the port the 863s I have.

DSRE

iTrader: (7)

I'm building an LM7 based engine for my self right now on a 6500$ budget and here is what i am doing just for some idea's for you
2003 LM7 5.3 block bored to 3.905, T-plate honed,ARP Main Studs, Decked to 9.235 575$
Scat Lightweight 4.00 stroke 24X reluctor 700$ from a forum
Scat Pro Comp 6.125 I-beams with arp 2000 bolt upgrade 360$ new
custom Arias Forged Pistons with hellfire rings 11.5:1 with 60cc, 1150$
Summit "Pro Race" SFI Damper 220$
Ported and shimmed Oil pump, windage tray,stock truck pan Time
LS2 Adjustable Timing set 80$
Comp XER Used Cam 232-234 .595i .598e 112lsa 110ilc 225$
Comp Pro Magnum Lifters used 80$
Crane Quick Lift 1.7 Gold Race rocker Kit comes with Push rods,guide plates,rocker studs and poly's, 450$ used
My Hand Ported Dart 205cc used alum heads 300cfm at .550lift heads have good springs,ti retainers ect found them at 900$ on a forum
Hand Ported Truck intake, literally cut in half ported then put back together=Time only
Ported TB 100$
K&N CAI 320$ new
Magnaflow Dual CBE 300$ used
Ebay Stainless steel truck headers with no cat Y 380$ new
Yank New 3000 Stall converter 550$
total spent so far is 6,010$ and i have a little more to get but so far i'm doing ok, I wish i could afford te Big LSX Block and all new parts but sometimes you just have to compromise!, goodluck with your build!

DSRE

iTrader: (7)

Someone did a back to back head test on a 5.3 with the stock 862's vs 243's "LS6" heads and they lost power with the ls6 heads because they have a little bit larger chambers, ive ported a few sets of 862's and they are a Great Head when ported for a 5.3, Blend the valve seat, do some bowl work,narrow the guide bosses, take out the rocker stud boss, lay it against the inside wall but don't over do it, then you can do some entrance work But be easy as the entrance is Plenty Large for even 300+cfm so don't make it bigger just to ake it bigger LOL!, Most important is sanding the short turn radius by hand with 80-120 grit emery cloth till you have a seamless transition into the valve seat, and for even better gains put in 2.00 intake valves and a nice 45* 3-5 angle valve job, this will help a Bunch over factory v-job, The ex port, blend seat, nice bowl job, raise exit a little, narrow guide boss, Sand Short turns, This is something a competent gear head can accomplish in a weekend and cost is minimal, It is a Very Rewarding job though, you'll gain 30-50cfm if your good and that will help tremendously on any engine, PS mill those 862's .030 and get over 10-1 on a stock 5.3 fwiw JMHO

v8envy

iTrader: (1)

I have 366 to the wheels with 799 heads basically the same as 243 heads so call the zo6 heads if you want, they are lightly ported, nothing wild never touched the bottom end, 400hp 5.3 is easy to build
L33 5.3 $500
Heads professionally ported $250
Ls6 intake $300
28.8 injectors $50
ls1 fuel rail $25
ported Tb $65 if you have yours ported
rx7 long tubes $800
CAI make your own $75
Tr224 112 LSA cam $225 used
valve springs $150
and most important good tune $250
$2690

BrownBoy

iTrader: (10)

That looks like an amazing build man! A bit more than I'd be looking to spend but still something to look up to for sure.

Yeah, I'm beginning to think that's what I'll end up doing except for possibly the bigger valves. Would the 863 heads flow well enough if I hand ported them but left the stock valves on it?

Now this makes me want to change my mind...

That's pretty much the same route I'll be taking except my block is iron.

Do you have any idea what your compression ratio is with those heads? Mine would be the same cause your L33 has the flat-top pistons I want to use.

v8envy

iTrader: (1)

Not 100% sure ont the compression ratio, I can look it up, if I were you I would post the LM7 in the for sale section and look for a L33 I have a spare one in the garage if your interested, better pistons, better head, and 70 lbs off the front end of that Fd3s, if you really want an iron block the 6.0 weighs the same and you can build a 400hp 6.0 real cheap in the end you will wish you had less weight in the front end, just my $.02

406malibu

I'm not sure what the CR would be with LS1 heads, but they have a larger CC than the 5.3 heads, so it would lower the CR. I'd stick with the heads you have now and mill them to up the CR a point or so. Sounds like an awesome build, with worked heads and a nice cam you should have no problem hitting your goal with stock internals. I would go with an ls6 intake rather than an ls1 intake though, they flow a ton better. Its a cheap 15 or so rwhp.

BrownBoy

iTrader: (10)

Sure, can you get it to my house for $500 with a tranny?

...that's why I decided on the LM7. It wasn't my first choice but damn, how can you turn that deal down?

The only thing I'm worried about is the smaller valves on the 862 heads might not flow as well and replacing them is pricey.

I'll have a bump in compression from the flat-top pistons and I'm not sure what would net me more power:

LS1 Heads: Better low but a smaller CR
Stock heads: Less flow but a higher CR

v8envy

iTrader: (1)

I have another set of 799s take them and have them ported, slap the ls6 intake on, and send the throttle body out to be ported, grab a used zo6 cam, mines not "alot" bigger and you will make very streetable power safely probably 325 to the wheels and thats a cheap combo, heads $250 intake $300 used zo6 cam $75 ported tb $75 bad *** amount of power in a FD