rebuilding my 89 iroc

[89iroc-z]

Hey guys, I have a 305 TPI motor that i spun a bearing in and it needs a new crank, but other than that, it runs good. So i wanna rebuild it and make it where it will rech about 325HP give or take a few, but atleast 300HP. So ive got a few ideas of what i could do, but i would like to hear what other people should suggest. AGAIN, any suggestions are fine.

thanks Tim

[Iroczlover]

lol drop a 350 in to it or bore out the 350 to a 355 & then stroke it. (every male strokes his engine)


My 87 Irocs 350 engine spun 3 main bearings 4yrs ago & I had it bored out to a 355 line honed it & also, had a LT1 crank & a Lingenfelter cam put in to it.

[NAHURRY]

I always loved them irocs!....Lots of gear heads on here maybe some will
chime in.

and welcome!

[r.i.p.01slpss]

If you're gonna keep the 305 then you should think bigger cam, some head work and intake work and hope for the best power wise. I wouldn't get too carried away with flashy internals or over boreing in a 305.

[Vash]

Better to get a crate or local rebuilt 350 long block IMO. That way you'll have now core and heads.

Rebuilding that 305 without bore and stroke and full parts rebuild in addition to your crankshaft as you said. Would be a waste of time and money IMO.

[99b4c]

It really depends how many miles are on the motor, its a waste to put a crank kit in a 100K+ motor IMO. If it has high miles I say go with a 350 shortblock with Vortec heads, Vortec TPI intake and a mild cam for the TPI setup.

Or swap in a low mile LS motor/trans and have the hp you want with a stock motor.

Whats the budget on this project?

[BlueZee28]

I think a lot of people forget that the power differences between the 305TPI and the 350TPI is extremely small.

If you're going to build a 305, and want impressionable power, you will want an aftermarket TPI system. Holley makes a great kit - Holley Stealth Ram. And since your motor is already set up for TPI, you won't need the whole kit. I do believe you can purchase everything YOU would need for around $800 and you can install it yourself.

I would recommend a moderate cam such has the LT4 Hot Cam. I have seen guys run this cam in 305's and it really wakes them up. But do remember that you will need to put new springs, lifters, pushrods, and get the heads ported to be able to use the extra lift and duration of the cam.

I would also highly recommend a stall for your transmission. (you didn't specify whether it was auto or manual, so I'm assuming auto). Something worth noting: TPI motors' power band is in a lower range than an LT1 or LS1, so keep that in mind when picking out a stall. Something around the 2,800rpm range would be beneficial, as you will still maintain a low lockup, and be able to use the low RPM torque.

Headers will be a personal preference. Some prefer shorty style, some prefer the long tubes. It is a general assumption that long tubes help more on the top end, and *may* decrease your torque/bottom end. It is also a general assumption for the opposite with shorty style headers. They will increase your bottom end, but will not give as big a benefit on the top end.


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Also worth keeping in mind: If you were to drive an L98 equipped car (350TPI), back to back with a LB9 equipped car (305TPI), you would be hard pressed to find a difference between the two judging by the seat-of-your-pants feeling. And the trap times on the 1/4 mile won't be much different either. Around here a well running L98 may run a 14.7-14.9

LB9's run around the 15.2-15.5 range here....mine ran a 15.0 with sticky tires and some know-how behind the wheel.


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Another assumption I'm going to presume is that you ARE on a budget which is why you're not looking into doing an LT1 or Gen III swap (LSX base). If I am right in my thinking, then you are on the right track, building a 305, as they can be done on a budget EASILY. They are much easier to modifty with less money than a newer block. I should know, I've invested about $1,500 in my 6.0 and necessary parts, and I haven't even bought my cam or had the heads ported yet, so the block isn't even put back together.

[Super83Z]

Originally Posted by BlueZee28

I think a lot of people forget that the power differences between the 305TPI and the 350TPI is extremely small.

If you're going to build a 305, and want impressionable power, you will want an aftermarket TPI system. Holley makes a great kit - Holley Stealth Ram. And since your motor is already set up for TPI, you won't need the whole kit. I do believe you can purchase everything YOU would need for around $800 and you can install it yourself.

I would recommend a moderate cam such has the LT4 Hot Cam. I have seen guys run this cam in 305's and it really wakes them up. But do remember that you will need to put new springs, lifters, pushrods, and get the heads ported to be able to use the extra lift and duration of the cam.

I would also highly recommend a stall for your transmission. (you didn't specify whether it was auto or manual, so I'm assuming auto). Something worth noting: TPI motors' power band is in a lower range than an LT1 or LS1, so keep that in mind when picking out a stall. Something around the 2,800rpm range would be beneficial, as you will still maintain a low lockup, and be able to use the low RPM torque.

Headers will be a personal preference. Some prefer shorty style, some prefer the long tubes. It is a general assumption that long tubes help more on the top end, and *may* decrease your torque/bottom end. It is also a general assumption for the opposite with shorty style headers. They will increase your bottom end, but will not give as big a benefit on the top end.


---------------------------------------------------------

Also worth keeping in mind: If you were to drive an L98 equipped car (350TPI), back to back with a LB9 equipped car (305TPI), you would be hard pressed to find a difference between the two judging by the seat-of-your-pants feeling. And the trap times on the 1/4 mile won't be much different either. Around here a well running L98 may run a 14.7-14.9

LB9's run around the 15.2-15.5 range here....mine ran a 15.0 with sticky tires and some know-how behind the wheel.


---------------------------------------------------------


Another assumption I'm going to presume is that you ARE on a budget which is why you're not looking into doing an LT1 or Gen III swap (LSX base). If I am right in my thinking, then you are on the right track, building a 305, as they can be done on a budget EASILY. They are much easier to modifty with less money than a newer block. I should know, I've invested about $1,500 in my 6.0 and necessary parts, and I haven't even bought my cam or had the heads ported yet, so the block isn't even put back together.

The HP difference is small, you are correct. The 305's biggest problem is that it is so limited in Heads. Vortecs or World Products would be the way to go on that motor, if you don't want to do the 350.