L36 to L67 swap

[maxbfresh]

if any one has any tips or links for a L67 swap into a 2003 gt currently with a L36 please my man help a brother out.haha but seriously ive got a list of parts i have but need to know what else is needed:
engine(L67)
tranny and axels
harness and cpu
subrame (is it needed?)
high flow fuel pump
the L67 rad and plumbing
what else is needed. any feedback would be great probably gonna pull the L67 on the weekend(hopefully)

[CrazyHorst]

It is not clear to me whether there are "body shop" differences (underbody variations) between a GT and a GTP. I suspect there might be different cradles but can't answer 100%.

I do think the easiest thing to do is to swap cradles (with everything else, eng, trans, driveaxles, steering and knuckles, etc) already together.

Again, my free advice is that I still think you will be money and time ahead buying a running GTP and doing some high-mile planned maintenance. Even if successful you may end up with a hybrid vehicle that only you can service and diagnose.

[grandprixgtx00]

what year is the GTP? as far as i know the cradle shouldn't be different. to tell you the truth it would be better AND easier for you to do a top swap. the L36 has much more compression than the L67.

[maxbfresh]

the problem is if i top swap i have a transaxel and bottom end built to handle 210 horses pushin 3 and change. ive alredy blew up a tranny and know it would be much easier with the s/c engine especially after mods. ive got a guy my bro knows has some nissan jdm engine in a 240 and his shop put a L67 in a fiero he said hes seen a bunch of gt/p's at the strip.(thats my term coprighted gt/p's) said i can use his lifts for the engine in and out and transaxel as well. im goin to compare the engine compartments side by side in a bit. just to look at the subframes and also like you got me paraniod about the steering system as well as the suspension.

[grandprixgtx00]

trust me...i did a top swap on my SE. it will by much easier on yourself. the bottom end of a L36 is just as tough as a L67. you can swap the axels out of the GTP because that is all that is really different between the 4T65E-HD and the regular 4T65E besides a few other minor things. if it really made you feel safer you could swap trannies too.

[maxbfresh]

what parts will i need for the top swap i know i need the lim, blower, fuel rails, custom pcm. but i was told i need the heads and do i need the headers to connect the down pipe to.

[tblake]

Yes, you will also need the heads. Plus you would have to be carefull what pulley you run as the L36 has a higher compression ratio due to the pistons.

I think the DownPipe will be a direct bolt in.

[CrazyHorst]

I think I'd be a little cautious about using the L36 pistons...there's a good reason the L67 has a lower compression ratio....knock.

If you plan to do any heavy-footed driving I'd strongly recommend the L67 compression ratio...the knock sensing will be trying to dump spark like crazy but you get to a point where a high-speed knock event leads to a hot spot that's happening nearly 50 times per second exceeds the piston's ability to transfer heat...and then very bad things can happen.

[BNaylor]

Originally Posted by CrazyHorst

I think I'd be a little cautious about using the L36 pistons...there's a good reason the L67 has a lower compression ratio....knock.

Take note of what was mentioned by people that actually did the top swap mods. You use a larger SC pulley - 4.2" which gives around 4 -5 lbs boost and that compensates with using the L36 bottom end with little or no KR but I emphasize the key there is supporting mods like intake and exhaust, etc.

Top swap and/or using the ZZP SS M90 kit are popular mods for L36 owners and have been around for years so nothing new or not well researched.

[tblake]

Originally Posted by CrazyHorst

I think I'd be a little cautious about using the L36 pistons...there's a good reason the L67 has a lower compression ratio....knock.

I thought you said that knock can't hurt a 3800?

http://www.automotiveforums.com/vbul...d.php?t=907899

[CrazyHorst]

Originally Posted by tblake

I thought you said that knock can't hurt a 3800?

http://www.automotiveforums.com/vbul...d.php?t=907899

Note the important distinction between a single event and the conditions where there are ~50 knock events per second (!!)

The great thing is that *anybody* can take off on their own personally-funded engineering development program. In IC engine design there is no "free lunch", many factors are balanced against each other, and so it is always possible to get a little more "x" at the expense of "y".

In generalities I find the following is true related to many types of machinery....

YOU PICK ANY 2:

1. High speeds/fast/power/impressive performance
2. Low cost
3. Excellent durability/longevity

[Mudtrux]

With a supercharger don't you want lower compression? = more room to stuff the volume of air/fuel mix. I know that's the ticket on older v8's

[BNaylor]

Originally Posted by Mudtrux

With a supercharger don't you want lower compression? = more room to stuff the volume of air/fuel mix. I know that's the ticket on older v8's

Not necessarily. It depends and there are many variables or dynamics involved regardless of if we talking about a supercharged V8 or V6.

Ideally, you want as much compression ratio and as much boost as you can run without running into detonation. Moot issue on a stock L67 engine since the GM engineers took care of that for us. Modding a L36 is a different issue since it has a higher compression ratio.

Obviously there is physics involved. The combination of supercharger boost coupled with your static or geometric compression ratio provides a resultant Effective Compression Ratio. Too complex for a typical discussion. Blah, blah, blah!

The bottom line is if you are willing to spend the money and exert the time and effort nothing wrong with putting a blower on a L36. Just another option. You just have to limit your boost so you do not destroy your engine and have supporting mods. Any possible knock retard (KR) should be constantly monitored after modding.