ok, in a nutshell, i have a Superam, Vortch blower and a blown motor. I was gonna get the goodwrench cate 260hp 350ft lbs, for $1300, (8.5:1 compression) and throw in a blower cam. I have trick flow 202's that i'd like to sell, 20k on them. what are they worth? and do you think this motor will hold up if properly tuned? i'll be running about 10lbs. boost. I have no money now for a better motor, and if i spent more on a motor, i would wan to get other stuff like DFI too. that's why i want this motor. Only drawback is the cast crank, and heads. it has lt1/lt4 rods and cast dish pistons. i f i don't do it this way, the car will sit for atleast 2-3 yrs/ thanks

 

buy a L31 (or any) shortblock and use the trickflow heads.

 

I did a search and saw that that motor has 9.1:1compression, and the only thing forged is the rods. It is also $1000 more than the goodwrench. Why do you say that this motor is better? And, if i got it, what could i easily sell the heads for. Is it stronger than the goodwrench. I am on a real tight budget here, I just wanna get the car going again. thanks

 

the L31 shortblock (p/n 12556121) is a new 4 bolt block that happens to be a roller block, its a "nodular" iron crank, and uses the powdered metal (PM) rods. it is 9.0:1 with 64cc heads, it costs $1,499.95 from SDPC2000.com

there is also the L98 shortblock (p/n 12510737) it is a New 2-bolt main block that is a roller block it also has a "nodular" crankshaft, but uses the same 1038 factory forged steel rods most of us here have stock. it is 9.1:1 with 64cc heads, it costs $1,135.95 from SDPC2000.com

remember there will be a little freight as well.

as far as the heads they go anywhere from $650 to $800 on E-bay which is actually pretty good considering the golden (half of new) rule you usually see on e-bay for any used part no matter how little it is used.

 

so, could you explain why you would use these motors instead of the one i was looking at? Isn't the 2bolt l98 even worse? I guess you have a good point w/ the l31, and then i could use my 66cc heads to drop the compression to about 8.8:1, right? My only question, is that even though it has better rods, the pistons are still cast right? and the goodwrench block has dish pistons, which should be better for my application, especially with my trickflows. Also, do you think that the l31 will make more power thank the goodwrench? I appreciate the info very much, I just want to make an informed choice. thanks a lot!

 

so, could you explain why you would use these motors instead of the one i was looking at?

The one you were looking at (the GM good wrech motor) you are paying extra for some 72cc heads that need to go in the trash, and it is a non roller block (all I have seen are and even if they have changed it doesnt mean you will get one) and they are almost flat top pistons not little dishes, but they dont come to top dead center and rarely have the indicated compression.

Isn't the 2bolt l98 even worse?

worse than what the L31? only that its 2 bolt but that hardly matters right now. Definitely not worse than the Goodwrench...

I guess you have a good point w/ the l31, and then i could use my 66cc heads to drop the compression to about 8.8:1, right?

I would say it would be close to that

My only question, is that even though it has better rods, the pistons are still cast right? and the goodwrench block has dish pistons,

your only question? - LOL Anyhow the L31 has slightly better rods true, all three of these engines discussed have cast dish pistons but some are more dished than others.

which should be better for my application, especially with my trickflows. Also, do you think that the l31 will make more power thank the goodwrench? I appreciate the info very much, I just want to make an informed choice. thanks a lot!


the L98 has the least dish so it will probably make the most power. it is the block all of us have started with basically if you had a TPI 350 to start its what you had.

 

Being that you say the goodwrench is basically crap, and non roller; I will choose between the l98 and l31. Originally i had a 9.5:1 summit 355, w/ 360hp and 410ft lbs. When I put the supercharger on is when the 355 took a crap. I never had a l98.
Anyway, the l31 has better rods, is a 4bolt and larger dish. The l98 has is cheaper. Assuming they will both be around 8.8-8.9:1 w/ my 66cc heads, it seems they should make the same power.. so, my choice is should will be tough. the l31 is probably slighlty more durable ( rods, 4bolt) and slightly lower compression, while the l98 is slightly cheaper. What are you thoughts on what is best. i appreciate it very much. All of the info is very helpful. Also, remember it's going under boost and the trickflows might need the larger dish in the l31. thanks

My final setup would be as follows: Either block, blower cam, Trick flow 66cc 2.02's, Vrotech supercharger (roughly 10lbs boost).

 

I would go with the L98 unless someone can verify that the L31 deck coolant passages dont need a modification (I seem to remember something about it)

 

Thanks very much for the opinion and info. Anyone else have anything to say? What is this about coolent passages btw? and oh yeah, one last thing. My trickflows are old style, non-centerbolt. They will bolt right up to the block right? The Superam fits no problem on those heads. thanks

 

Are you really SURE you don't want to get a real blower-oriented short block? Cast pistons and blowers..... not a great match. (Keep in mind that I run KB hypereutectics with a blower now, but I still don't recommend it. How's that for NOT walking it like I talk it?)

I mean, 10 PSI is no joke. Little detonation from running lean or too much spark advance and it's gonna go "boom" pretty quick. And your compression ratio (~9:1) is, in my opinion, still maybe a little high and might be on the ragged edge for pump gas.

I understand being on a tight budget but there's such a thing as being penny wise and dollar foolish.

I'm not saying you need a forged crank or even upgraded rods but a blower bottom ends are more than just forged pistons. They also usually have a little more dish to the pistons, they open up the ring gap a little to cope with the extra heat generated in a boosted motor and usually they run the bearing clearances a little tight vs. a N/A application.

I'd just hate to see you shell out $1200 for a new bottom end just to have it grenade again later this summer.

 

It's kinda funny, but budget used to NEVER be a problem. Then I went and bought a house, and booked a wedding hall. Damn expensive. I have layed out 100k in the last year, easy. This leaves me real tight and still in debt to the mortgage company. So, normally i would go out and build the right motor. The problem is, the more I spend on it, I'd want to have it tuned by someone and get DFI instead of MAF. It'll all add up to atleast $4000, maybe $6-8,000. So, i can let the car that is in perfect condition rot, and let all the great parts like the Vortech and the Superam sit in the garage,,......OR i can get a $1200 motor, drive it carefully, make sure it's in tune and atleast use the car. I would even get the smaller pulley if hey make it. Right now I ahve a 10lb and 15 lb pulley. Just so i can atleast drive the car. not to mention, if I do a real blower motor, i need a new tranny because mine is shot. But to make a long story short,... I won't have money to get he car on the road for ATLEAST 2-3 yrs from now, UNLESS I go ahead and buy a $1200 motor. So it seems like a no brainer, if it doesn't lean out and it's in tune. But your point is very valid, altough this is the only situation i can see making me happy, I think. I'll have to take the chance. The general felling is that i will run aluminum TF heads, so the 8.9:1 comp should be ok i guess, even if I have to run the 6-7 lb pulley. I'm really hoping that driving it carefully and only under 1000 miles will make it last. Lets face it, guys have run blowers on L98's before, even ones that have miles. So I'm hoping it's worth the chance. Anyway, that's the whole story, so any advise is appreciated! ANYONE have any?

 

Cast pistons aren't as bad as everyone says they are. A bad tune will ruin a forged piece also. Running 8.8 to1 on cast pistons with a very good tune on 94 octane at 15 psi shouldn't be a problem. Make sure you have an intercooler and don't beat it till it's tuned.

With that being said, you say you have a set of heads already. you may also want to look into a partial motor. What happened to the 355? Rod broke,piston melted,main bearings failed,etc. It may be cheaper just to clean up the cylinders,the crank,rods, and put a set of pistons in there. A stock crank should get you to 500hp. Look at all your options before throwing big money at a little problem.

There's always an LC2 out there for ya! JK!

 

that is very very good advise. Thanks a lot! ,... just what i needed to hear. I wanted to fix my motor, but everytime i talk to the machinists, they up me from $1000 to $4000. So i figured the l98 would be good w/ my trickflows. I guess I should see what's srong w/ my block. thanks gain
oh BTW, i woun't be running the 15lb pulley, but i'll be using the 10lb, and running 94 octane and like you said in TUNE