sloan

Anyone familiar with a LT1 to LT4 conversion? I am considering upgrading a 93.

Will it pass California smog?
Doe it change the compression ratio?
Torque curve?
Worth $2000?

Appreciate any info that you may be able to provide.

Mez

This subject has been discussed many time before. Since virtually all moving parts would require changing, it is not worth it. If you are looking for the performance gains, CNC ported LT1 heads, roller rockers, and cam change would give you about the same results for a lot less effort.

sloan

I am not talking about a complete conversion. Rather the quick LT4 upgrade that Jim Pace sells for about $2000.

Which if you did your homework includes the very parts that you mentioned.

Mez

Sorry, but I DID my homework. You were not specific about the Jim Pace conversion package in your original message.

As an owner of a LT4, I know there are many more parts that need changing to do a full convertion ti an LT4. These include:
Pistons (higher compression)
Piston Rings (positive twist for oil control at high RPM)
Timing gear and chain
Crank Shaft (rolled filet)
LT4 Heads
Cam
Roller rockers
Intake manifold
Knock sensor
Computer & 8000 rpm tach (to bump up rev limit to 6400 rpm)
...and thats just the major parts.

I take issue with anybody's claim that simply changing the heads, intake, rockers, and cam qualify as a conversion to an LT4.

If you are looking at upgrading your LT1 with LT4 heads, intake, roller rockers, and cam, I still suggest looking at porting your LT1 heads, Crane roller rockers, and cam change.

Silver 96

Mez:
I thought I read somewhere that the LT4 has 4 bolt mains vs 2 for the LT1. Is this correct?

Phil-tha-Rush

that is a somewhat MORONIC comment to make when asking for help.

An LT-4 for $2000??
yep, someone should do thier homework alright.

mez has the right idea about upgrading the LT-1.

mackeyred96

Just upgrade what you got. It's much more cost effective. That's what I did.

sloan

The conversion I spoke of is sold by Jim Pace performance, and if you had done your homework instead of writing egotistical replies you would have noticed that it includes the very parts you mentioned.

Does anyone, other than Mez, have experience with this kit or any other?

ChrisB

I also believe that, bang for the buck anyway, you will be much better off (read: faster) getting your stock heads ported by a well known porter (makes sure it's one who has LT1 cars running well he can point out) and a custom camshaft.

corvette dude

wow, sloan with the way you ask for help I would not expect much of it!!!

SouthernSon

Evertime I see a terse response to a post, I always look to see if the previous post was edited. As Paul Harvey might say, "where is the rest of the story?"

93Polo

The kit comes with Lt4:
Heads
Intake
Roller rockers
LT4 hot cam not the stock LT4 cam

The conversion keeps the stock shortblock and has been done thousands of times with great success.

With that said I would still recommend ported heads LT1, and cam from your favorite shop LPE, DRM, Agostino, MORE, Morgan in CA etc. The ported LT1 heads will give around 30 more rwhp more than STOCK LT4 heads.

olephart

Wow!

EARTH TO SLOAN- 5 VERY KNOWLEDGABLE PEOPLE HAVE TOLD YOU THAT IT IS BETTER TO PORT THE LT1 HEADS AND ADD THE CAM AND ROCKERS.

Plenty of stuff about it in the archives - do your homework.

JasonL

Bob, the Vette LT1 has 4-bolt mains as well. The LT1s in other platforms (B-, D-, and F-bodies) are 2-bolt mains.

sloan

Thanks for the responses (some of them were more helpful than others).

Since the general consensus is to port existing heads, does anyone have any recommended flow volumes?

Also although this modification is not legal in California has anyone tried to smog this combination.


PS Mr. Mez if you take issue with this being called a LT4 conversion I suggest you contact Jim Pace Performance at (866) 875-5862 and voice your concerns. I'm sure they will give your comments the merit they deserve. Labeling this an LT4 conversion is a description out of their catalog.

93Polo

Sloan is new give him a break. As I am only 24, I remember being new to the scene.

http://www.mmsracing.com/april_2001/index.html
http://www.dougrippie.com/ and http://www.lingenfelter.com/ have 50 state legal packagages.

Lamar

Mez

Most definitely this package falls short of a LT4 conversion due to the many missing parts. But I'll pass on calling Pace. If I called every retailer that made a similar statement, I'd be on the phone 24 hours a day. All I can say is know what you are buying and shop around.

This is really a "top-end" package, which you may want to visit Lingenfelter or Doug Rippie to see what they offer in a similar configuration. Its worth checking it out.