Hello everybody

I own a 1989 Z51 with manual transmission. The car is listed at 245 HP. On my 1984 the intake was a restriction, so I ported it. On the 1989. Is there one thing that creates a bottleneck and restricts the horsepower. Just wondering if there were any simple mods that would yield big gains. I would like to get to 300 HP.

Thank you,
Joe

 

Exhaust will probably be the quickest way to add power. But getting to your target goal will require engine mods such as cam, heads, and intake. Then a good tune.

Are you required to have the car emissions tested? Headers and true dual exhaust alone will provide a decent gain. But getting a shop to install true duals and removing the cats may be difficult. If a shop gets caught removing working cats with no intent on replacing them, the Feds can hit them with a 5-figure fine.

How many miles are on the engine? It may be that if the engine has high mileage, it would be worth having a reputable engine shop build a motor or buy a replacement performance engine. A GM ZZ5 long block would be a good choice or a Blueprint engine. Search thru the Summit Racing website for some good long blocks that will give you at least your 300HP goal.

 

Actually for now I am trying to keep it simple just bolt on HP. The exhaust is a great idea. NJ just passed a law that vehicles over 25 do not have to go to inspection any longer. Any suggestion on headers on headers and such.
Is the throttle body and intake a restriction like the crossfire intake.
I did not figure I would be able to bolt on 300 hp. But, a little boost without a big expense would be great.
I would like to supercharge it next year, nothing too big just a few pounds of boost. like I said 300/350 is enough.

Thank you

 

x2 on headers,exh leave the TB alone
If you can port and want power on the cheap

Used aftermarket runners
Heavy porting to the stock base
This with exh should net you a solid 13 sec runner
add
Head porting if youre up to it keep the stock valves
Small cam
Tune
This is usually when it all turns into a big expensive can of worms

 

I am sorry X2 is a header brand? I thought that porting may help. I want to put real roller rockers in. Do I stay with 1:5 or go 1:6.
After market runners. There are about four options any suggestions. This is going to be a street car. maybe some performance driving once in a while.

Thank you all

 

x2 meaning I agreed with the previous post

ASM runners are nice if you can find them..accel are Ok
If you do rockers do springs & seals while youre there not worth it personally sure it gives a lil something though

 

IMO...If your plan is to supercharge engine, I would find compatible parts for that mod. Forced induction will take care of the TPI intake issue. I would do the free flowing exhaust 1st.

 

I installed Hedman Elite headers on my old '87. Summit Racing has good prices. Any compentent muffler shop can install true duals and mufflers. I used DynoMax UltraFlo mufflers. Nice sound at idle and cruise.
You can also remove the AIR system. There won't be any HP gain but it does clean up the engine compartment. But you willl have to fabricate a lower support rod to keep the alternator from breaking the factory aluminum bracket. You will also need a slightly shorter (2") serp belt if you go with an AIR pump removal kit such as the TPiS kit.

The '89 Hitachi-style starter should work with the headers. Can't hurt to use some heat shielding around the starter and the two fuel lines. You will most likely have to fabricate a new mount for the oil dipstick tube.

It would be a good time to install new plugs, wires, and a cap and rotor. Taylor wires will work fine and go with a good quality cal and rotor with brass contacts.

The OEM throttle body will handle close to 400HP so unless there is something wrong with it, just keep it.

Port-matching the intake runners can provide a few HP gain. But to get serious power, your best bet will be new heads like AFS heads, TPiS Miniram intake. A good cam selection, injectors to match the intake system, and a tune.

A blower would be a good bolt-on power adder, but it will certainly make things tight in the engine compartment. One thing to consider is the age/mileage of the engine. A blower, even with lower levels of boost like 6-7 pounds, can take out a weak bottom end quickly. And if the intake side is weak such as worn valve seats, weak springs, worn cam and lifters, a supercharger can quickly make things go south.

 

Dido on the above recomendations. I noticed a HUGE difference when I switched to the MINI and changed the tune. Did a few other mods but you always want to get more air in and out to enable more horsepower.