Vortec to LT1?

MoJo · July 16, 2003

Since the '98 5.7L is TPI, is it possible to change it over to an LT1 intake? Has anyone tried? Or am I barking up the wrong tree?

Seems like it would help the HP, torque and mileage.

robsawatsky · July 16, 2003

The fuel injection systems for the truck 5.7 engine and the LT1 5.7 are different. The truck has a central fuel injector with "poppet valves" for each cylinder, the LT1 has true individual port injectors.

Rotorwrench · July 16, 2003

The way the coolant flows through an LT1 is completely different than a Vortec. You cannot put an LT1 intake on a Vortec. No coolant flows through the LT1 intake manifold and the thermostat is mounted in the water pump.

MoJo · July 17, 2003

Thanks!

americanmuscleman · July 17, 2003

Like they said, you really can't put an LT1 intake manifold on anything except an LT1.

The main reasons are:

LT1's use a front mounted distributor, so there isn't a hole in the back of the intake for a distributor like a normal SBC uses.

As stated above, the LT1 intake is a dry manifold, and coolant isn't circulated through it. Coolant is circulated through the throttle body though.

The LT1 intake's four center bolts are at a different angle than on a normal SBC. These can be drilled to match regular SBC heads, but its a hassle.

A company called Tuned Port Injection Specialists ( www.tpis.com ) sells an LT1-style SBC Mini-Ram with fuel injection and computer software to tune it. Accel and Edelbrock also sell similar systems. GM also makes the Ram-Jet intake which you can now by without having to buy a whole Ram-jet intake.

TPI (Tuned Port Injection) was used in the 84'-91' Corvette, and 85'-92' F-bodies. Its the big "spider leg intake".

GM used the TBI (Throttle Body Injection) from 87'-95' in GM trucks. 96'-99' C/K GM trucks got the Vortec SPFI (Sequential Port Fuel injection).

Hope that helps

ShortCrew · July 17, 2003

Mojo,

I think you would be much better off going with an Accel MPFI system. They make a complete kit to upgrade your truck. It comes with manifold, throttle body, injectors, PCM, everything.