5.0 Eater

iTrader: (2)

Hey fellas, I currently have an 89 iroc w/ a 383 hsr etec 200 heads and a t56 trans. This makes a pretty fun street car but where i live there is a terrible infestation of ls1 forth gen car sneaking into the 11's. I nearly got sucked into buying a lq9 and starting a build up that route. I know, it was close. (lol) I am however a lover of high tech hp, I can see the draw of so many people to the lsx based engines. I absolutely refused to switch to a carb but i still wanted to make good power so i got rid of the old obd1 computer and switched to Mike Noonans obd2 set up that allows me to have sequential injection, control of 4l60e or 4l80e trans and still have the tuneability of the late model 0411 ecm. This setup works well, but i have found myself lacking when parred up against many lsx cars lately. I fully unerstand I could build a big cid sbc and kick the crap out of many lsx motors but i don't want something so ratical that i'd give up a bunch of street manners. Here is my plan.

I'm using a mark vi because i plan to keep my obd2 ecm and the late model block uses a crank sensor i can use with my computer. The block i bought has all 5 4 bolt mains. I wasn't aware gm did this untill i removed the pan. I got a forged 4.25 stroke 1 piece rms internally balanced crank on the way. I decided to stroke it to get some more cid. It will get some i beam 6.385 rods and around 10.0 to 1 forged pistons. Allunimun Heads, around 300 cc runner. ( need some advise on heads) I want a head and cam combo that can support around 600 hp at no more than 6500 rpms. Has to be a well mannered motor on the street that will get a little bit of bottle use from time to time. Against those really stubburn lsx cars.

t-top havoc

iTrader: (3)

Sounds like FUN! There are a few bigblocks in this site. I don't know how many are injected. The head/cam selection is mind-boggling! 300-325cfm for street w/a .680 lift 295-302 duration would probably have a max rpm around 6300-6500 I'm guessing- I don't understand it all, just that heads/intake/cam play together-miss match and performance suffers. You will most likely hear from people that KNOW this stuff real soon! I wish you luck!!

AlkyIROC

My 2-1/4" primaries fit inside the framerails but they're not cheap. For your application, 1-7/8 are probably more than enough.

My engine is injected but it's a mechanical injection system.

I don't think you'll find any 300cc heads unless they're a factory production head. The majority of the aftermarket heads are 310/320 minimum.

5.0 Eater

iTrader: (2)

Yeah I think the 1-7/8 patriots will work fine with a little tweaking. The heads i was considering were the edelbrock victor jr. 24* #77479. They have 300cc intake runners but they only flow 342 at .600. The victor series may be better with 340cc and flowing 369 at .600. About the same price too.

AlkyIROC

Oops. Sorry. I wasn't thinking about the size of oval port heads.

Stick with the smaller head. Your still only building a small engine.

5.0 Eater

iTrader: (2)

No problem those are rectangular port heads, I only wanna go with a 489 because the mark vi doesnt run as thick of cylinders so going .060 overbore might make it run hot on the street. I think I'll use edlebrocks 2262 h/r cam 236-245 .625-.639 cam and the victor heads and victor jr efi intake. Should make good power and tons of torque. With the od and some 3.25 gears it should be a good cruiser too.

5.0 Eater

iTrader: (2)

Got my engine in today. I'll get pics soon. I had no idea all 5 mains were 4 bolt on these blocks. It came with the fi intake, alluminum valve covers, BIG o'l manifolds, pistons, rods, crank, all the electronics, ls style tb, balancer, flex plate. All for 400.00 Heck of a deal i'd say. Oh and has anyone run the patriot 325cc rect heads?

5.0 Eater

iTrader: (2)

Here's some pics of the block with my new stroker crank.

5.0 Eater

iTrader: (2)

Here's a few of the stock intake. I'm not gonna use it but its kinda cool. For sale cheap if anyone wants it.

5.0 Eater

iTrader: (2)

Couple of the manifolds. Pretty big ports, might use them, probably not.

5.0 Eater

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Couple other pics, can't wait to get this thing together.

Parasoth

iTrader: (1)

Subscribing. (You have not mentioned how much you wanna spend on the trans) Any thought to have the gears in the T-56 made taller? I have thought long and hard on this dilemma, and what I am thinking is with that power, your going to be able to just speed up to your desired speed, pop it in 6th and cruise. So why not match 1-4 to how you need it and leave 5 and 6 as they are, maybe tweak them a little bit to match coming out of 4th into 5th and so on if you need it.


I mean going through the traps in 3rd with a T56 BBC would be awesome in my opinion, 4th if you have to, and on the street its going to pull forever.

I would also hate cruising around with an auto at that level with the gear you would probably want to run at anything over 50.. lol maybe you if full exhausted it with some extremely quiet mufflers on it and just ran some cutouts. That would be pretty sick.


Your also right at the power I am wanting to make before I put a fat 'ol turbo on it.

I have heard the manifolds can work, but for 600HP, I would at least look at the Partiot's mentioned in the sticky. Maybe even so far as the Hookers.

EDIT: Didn't notice the 3.25 gears. Is it a DD?

5.0 Eater

iTrader: (2)

The best fix for the t56's gear ratio problem would be a lower first gear. I have found that with a 26in tire and a red line of about 6500 rpm's 3.73 gears is as low as you can go. 28in tires can go around 4.10. The problem for me is even with low rear end gears, you still have to slip it a little to take off smooth in first. A deeper first would allow you to run taller rear gears and get you efficency up. A 320 something first would be perfect. I'll use 3.42 rear for now with my t56. That will make it a blast on the street. When its time to go deep into the 10's I'll probably need to go with an auto, like the 4l80e. My main goal is to keep this thing streetable, i.e. no 4.56's and 3 speeds.

5.0 Eater

iTrader: (2)

I have decided to go 496 (4.31 bore, 4.25 stroke) Gonna run the 1-7/8 patriots unless I can modify the hookers to stay inside the frame rails. Probably going to go with the patriot 320cc alluminum heads also. Still working on the serp set up. Let me know what you think.