1998 GT Engine advice STOCK to TWIN TURBO

cuzins101 · Mar 10, 2017

Although this is my first post, I have been doing A LOT of reading on here. Thanks to all the people that took the time and effort to put out information!
So the question is this:
I am ready to start adding horsepower and eventually run twin turbos (ON3):
Where is the logical place to start?
If I'm going to do a full PI swap, should I just pull the whole engine (185,000ish miles {odometer stopped at 150,000}) and have the machine shop go over it?
Should I buy ebay PI heads, should they be pressure checked before install?
The fuel pump is currently dead and I was going to replace it with the Walbro 255LPH. Thoughts?
ANY suggestions are welcome, thanks in advance!

evilcw311 · Mar 10, 2017

You better have a pretty stout bottom end built if you plan on running twins and any kind of boost numbers. A single 255 will be nowhere big enough for the kind of numbers most people would aim to generate with a set of twins.

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the5.ohh · Mar 10, 2017

Coyote swap it.

96blak54 · Mar 10, 2017

Go ahead and twin turbo what you have. Yes, the stock engine will not survive "if" you boost it to hard. Here is my thinking...

1. $5,000 engine
2. $5,000 turbo
3. $700 dyno tuning
4. $500 rear tires
5. $300 clutch
6. $500 revamped fuel system
7. $500 for guages to monitor
8. $400 aftermarket k-member

You see, this list can keep going.

If you are set on a twin build, move forward with whats already running. This way the cars doen time will be minimal.

Honestly, 500rwhp is plenty good on the streets

cuzins101 · Mar 11, 2017

I'm the original owner and really wanted to keep block.

cuzins101 · Mar 11, 2017

Yeah, that was my concern, that the cost would just keep growing!

96blak54 said:
Go ahead and twin turbo what you have. Yes, the stock engine will not survive "if" you boost it to hard. Here is my thinking...

1. $5,000 engine
2. $5,000 turbo
3. $700 dyno tuning
4. $500 rear tires
5. $300 clutch
6. $500 revamped fuel system
7. $500 for guages to monitor
8. $400 aftermarket k-member

You see, this list can keep going.

If you are set on a twin build, move forward with whats already running. This way the cars doen time will be minimal.

Honestly, 500rwhp is plenty good on the streets

g36 monkey · Mar 11, 2017

The reality is the engine internals will turn to dust with much more than 400 horse. If you have twin turbos 400 will be like with a bottom of the bucket tune that is not any good. Any decent twin turbo setup would net you much more, and you would be far overpowering your rotating assembly.

It's not necessarily a bad idea to install them on the stock motor and start getting the kinks worked out, but doing so knowing you will have to pull it all for a rebuild when the motor blows.