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Toyman01
Toyman01 SuperDork
1/17/11 5:46 p.m.

As some of you might remember my son blew up my FB RX-7 several months ago. Needless to say I have dreamed up multiple ideas for repowering it. Due to costs a rotary is out. As much as I love the scream of a rotary, the dollars per HP just don't add up and I still have the Abomination to scratch that itch. I managed to score a T56 six speed last week for $200 out of a Z28 Camaro. That is going to be the start of the build. The next natural thought is LS1. They are pricey and complicated for a neanderthal like me so short of a squeal deal falling into my lap they are probably out as well. LT1 is the next step, but I have heard nightmare stories about the electronics on them. SBC is the next step and sounds appealing to me. The car will be mostly street driven with the occasional autocross. The A/C is probably going back on also. No A/C in the summers around here means the car just sits during the summer.

I have two Chevy 350 blocks. One is a car engine and the other is a very low hour Mercruiser marine engine. The car engine will need a complete build, the marine engine will need the heads gone through due to a boat fire. If my memory serves me correctly the marine engines have forged internals. So, using the marine short block, build me on paper a moderate HP high torque SBC. Something in the 300+hp 400+tq range sounds like a lot of fun in a first gen RX-7. The compression ratio on the marine engine is 9.4 to 1. The heads on it now are 64cc "217" heads.

Bobzilla
Bobzilla Dork
1/17/11 6:10 p.m.

What about a truck LSx Vortec engine? THe 4.8 is a short stroke engine that I've always thought would be great with a big hairy cam. Make it a high rpm screamer using an LS6 intake manifold, Comp Cams bumpstick and the wiring harness/ecu out of the truck would make it economical and easy to do....

EDIT: the truck engines are quite a bit cheaper usually. Plus, even the "lowly" 4.8 made 285-295hp/295tq stock. Cam, intake and ECU work would make it an easy 350/350 engine that could rev to the moon IMO. The 5.3 uses the same bore size but a longer stroke, therefore made more torques and almost the same hp (295hp/315tq). The 6.0 LQ4 uses the 5.3's stroke and a larger bore. What about a 6L block with the 4.8 crank to make a hybrid short stoke rev-motor?

wheelsmithy
wheelsmithy Reader
1/17/11 6:14 p.m.

LS4 and a hood scoop? Cheap aluminum heads for that mercruiser. Anyway, Doesn't sound like you can go wrong.

Strike_Zero
Strike_Zero HalfDork
1/17/11 6:17 p.m.
Toyman01 wrote: I managed to score a T56 six speed last week for $200 out of a Z28 Camaro.

How the heck do you find deals like this??

By the way . . .I approve of this

LS1 = $$$$

Any Gen III/IV V8 will soothe primal instinct for less buy in than the LS1. $1500-2000 for beat-up LS1 = no way in hades . . . 5.3 or 6.0L will perform just as well with the same LS1 bolt ons and performance goods.

The LT1 is not a scary motor. The opti-spark issue a well documented and overly misunderstood. Get the vented one and keep the water pump from leaking on it. Simple fix . . .

Other than that . . . I approve of the V8 in an FB

Strike_Zero
Strike_Zero HalfDork
1/17/11 6:21 p.m.

In reply to Bobzilla:

I'm with you on building screamer GenIII. Get a 4.8L for $2-300, nasty cam, LS6 intake, 243 heads . . . shouldn't break $1500. This would absolutely scream in an FB!!

Bobzilla
Bobzilla Dork
1/17/11 6:23 p.m.

^ I want one in my C4.... it's a little heavier than the FB, but would still be one helluva shot in the arm for power.

aussiesmg
aussiesmg SuperDork
1/17/11 6:23 p.m.

I have two and can only say one thing

DOOOEEETT

TuffWork
TuffWork New Reader
1/17/11 6:35 p.m.

If I were you I wouldn't get overly complicated. I would find a 350 vortec from a truck and put an intake manifold, cam, distributor, coil, carb it and be done with it. You will have about the power numbers your looking for without much hoopla or cost.

bluej
bluej HalfDork
1/17/11 6:36 p.m.

http://en.wikipedia.org/wiki/GM_Vortec_engine#L33

2005 Engine GMC Truck Sierra 1500 GMP102 $850 Sunshine Auto Salvage USA-SC(Orangeburg) Request_Quote 803-531-1008 Request_Insurance_Quote 73

too much?

Strike_Zero
Strike_Zero HalfDork
1/17/11 6:43 p.m.

In reply to bluej:

That's in the range (high side). I see them from $500-900.

It comes with the hot GM heads as well . . .

Schmidlap
Schmidlap HalfDork
1/17/11 7:54 p.m.

The T56 out of a LT1 Camaro is not the same as the T56 out of a LS1 Camaro, so make sure you know which one you have before buying an engine for it. I'm pretty sure that making a LT1 trans work with a LS1 engine (or vice versa) requires swapping the input shaft (one is longer) and changing the bellhousing. I'm not positive though, so do some googling before committing.

Bob

Toyman01
Toyman01 SuperDork
1/17/11 8:03 p.m.

In reply to Schmidlap:

You are correct. Much google fu is being used tonight. Through much mixing and matching of parts and or adapters most of them will fit on most others.

Xceler8x
Xceler8x SuperDork
1/17/11 8:20 p.m.

Are the truck SBC's iron blocks? I'm wondering about weight vs the tried/true LS1.

Toyman01
Toyman01 SuperDork
1/17/11 8:29 p.m.

The L33 and the LM4 are aluminum, all the rest are iron block, aluminum head. A quick search says there is about an 80 pound difference.

MrJoshua
MrJoshua SuperDork
1/17/11 8:30 p.m.
Xceler8x wrote: Are the truck SBC's iron blocks? I'm wondering about weight vs the tried/true LS1.

Most are, the L33 referenced above is not. 75-100lbs difference.

Toyman01
Toyman01 SuperDork
1/17/11 8:59 p.m.

Here is some pretty good info.

For the 1996 LT1 and 1996 LT4: 1003. LT1 Mass: 576 lbs LT4 Mass: 603 lbs

For the 2001 LS1 and 2001 LS6:

LS1 Total Dressed Engine Weight: Auto. - 457.6 lbs. (208 kg); Manual - 497.2 lbs (226 kg) LS6 Total Dressed Engine Weight: (Manual only) - 497.2 lbs (226 kg)

For the 1989 L98:

Total Dressed Engine Mass (Dry Weight) -

Automatic Trans: 541.2 lbs (245.5 kg) Manual Trans: 592.2 lbs (268.6 kg)

For the 1990 - 1992 LT5:

Total Dressed Dry Engine Weight: 270.5 KG (596 lbs)

HiTempguy
HiTempguy HalfDork
1/17/11 10:07 p.m.

I'm curious as to how high you can rev a 4.8L (lr4 or Ly2, I'm not picky). The L33 (from what I understand) shouldn't be put over ~6500rpm. If I could get the 4.8L to 7500rpm (or higher mostly for E36 M3s and giggles) with the right valvetrain, I'd stick one in the Volvo this spring.

Strike_Zero
Strike_Zero HalfDork
1/17/11 10:15 p.m.

In reply to HiTempguy:

4.8L + patriot springs + ARP rod bolts + LS7 lifter = 7500-7800 rpm . . .

bluej
bluej HalfDork
1/17/11 10:21 p.m.
Strike_Zero wrote: In reply to HiTempguy: 4.8L + patriot springs + rod bolts = 7500 rpm . . .

are the 4.8's all alum or iron/alum?

Strike_Zero
Strike_Zero HalfDork
1/17/11 10:24 p.m.

In reply to bluej:

Iron block. If you wanna get funky . . .get an aluminum LM4 or L33 block and stuff it full of 4.8L goodies.

The LM4 would need 4.8L pistons, rods, and crank. The L33 will need 4.8L rods and crank since it is using 4.8L pistons for the higher compression . . .

Strike_Zero
Strike_Zero HalfDork
1/17/11 10:31 p.m.

Another thought . . .if you get a LY2 4.8L, it should come with the 243/799 heads . . .

The LY2 is rated at 302/305 . . . but they are a higher buy in last time I checked. . .

HiTempguy
HiTempguy HalfDork
1/17/11 11:40 p.m.
Strike_Zero wrote: Another thought . . .if you get a LY2 4.8L, it should come with the 243/799 heads . . . The LY2 is rated at 302/305 . . . but they are a higher buy in last time I checked. . .

Here in canuckland, motors don't so much vary by each individual one as they do "family" (like 3rd gen vs 4th gen small block). As such, an LY2 is the same as a L33 ($1000cdn, under 60k miles). The LM4 is a bit cheaper due to soooo many of them being available.

Anyways, my friend and I decided that since we are no longer doing chumpcar, and the volvo is cleaner than we thought, that we are going to do either a L33 or LY2 swap with a T5 (that geforce tranny got me thinking). Will probably end up going with the LY2 if we can hit almost 8k rpm as we just want something that is stupid (wayyy too much rpm, wayyy too much cam for the street, 4.53 rear etc). Loud exhaust, a bajillion rpm, throw all of the ipd suspension stuff at it and go do all the time attack days this summer.

Strike_Zero
Strike_Zero HalfDork
1/18/11 12:00 a.m.

Hehe . . . That's what's up!! A ton of RPM and big rear gears!!!

tuna55
tuna55 Dork
1/18/11 6:52 a.m.

Why do you guys want RPM so badly? He wanted cheap. Cheap and RPM are mutually exclusive. Luckily, power and cheap are not.

Bobzilla
Bobzilla Dork
1/18/11 7:17 a.m.
Schmidlap wrote: The T56 out of a LT1 Camaro is not the same as the T56 out of a LS1 Camaro, so make sure you know which one you have before buying an engine for it. I'm pretty sure that making a LT1 trans work with a LS1 engine (or vice versa) requires swapping the input shaft (one is longer) and changing the bellhousing. I'm not positive though, so do some googling before committing. Bob

tHIS. If you find you have the LT1 trans I'll be more than willing to give you $300 for it.

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