89TramsAmGTA

There has been some interest on the Comp XFI series cams. I have the XFI268 on my L98 TPI 355 motor. Here are the dyno results. 401rwhp@6050rpm and 390rwtq@5300rpm.

This is through a 700r4 transmission and a YankSS3600 torque converter and 1 3/4" shorty headers.

These are preliminary results. Dyno tuning yet to follow.

mako350Z28

What intake are you using?

Hell, what parts are you using period?

91Z-28

Nice, I was hoping to make 400rwhp with the 280XFI. Now I'm stoked.

confused327

what heads?

the rest of the setup?

89TramsAmGTA

Here is the basic list of parts. The plenum is the factory GM part but opened up for the Holley 58mm throttle body and the runners. The runners are highly modified SLP's that are fully siamesed. The intake is an Extrude Honed Edelbock with some opening up at the runner side.

The heads are Dart Pro One 200cc that have been massaged. Running 10.75:1 compression with 8.5:1 DCR. Comp Cams Pro Magnum 1.6 rockers, 918 beehive valve springs, Terry Manton 3/8" number 4 pushrods and GM roller lifters.

The headers are 1 3/4" custom shorties by Dyno Don. Custom exhaust following the factory pattern to the Y pipe. Magnaflow 2 3/4" metallic dual cats. Mufflex 3 1/2 inch exhaust. Magnaflow 3 1/2" muffler. Custom 3 1/2" cold air intake.

700R4 transmission. Yank SS3600 converter and 3.70 gears in the nine bolt rear end.

I'm really surprised at the 6050rpm peak HP. The dyno operator let off at 6150rpm and it was still over 400rwhp.

By the way this is a fully smog legal California car.

confused327

that is pretty impressive from a tpi type intake.

what does the curve look like?

89TramsAmGTA

For those interested I have a posted the graph and table on 3Rd Gen.org.

Here is a link to that thread. http://www.thirdgen.org/techboard/tp...-tpi-dyno.html

seawolf06

Why did he stop at just 6150? I wanted to see how long it would hold that hp, especially with those springs. Very nice.

91Z-28

Are those #s STD or SAE?

seawolf06

It says 1.1 SAE correction factor, so hopefully they're STD.

89TramsAmGTA

Yes that is with the SAE standard correction factor. This was the first time on the dyno and I wanted to get a baseline of where the motor was at with the latest buildup. We were taking baby steps with the rpm and 6200 was the highest we were shooting for with the XFI cam and untuned.

We had no idea the motor was going to still be making that kind of power in the 6000 rpm range. So the next time on the dyno we will be doing tuning and will extend the range a few hundred more rpm. The results were totally unexpected by all involved.

91Z-28

Keep us posted, I'm really interested in how far you take this motor. People have been telling me I can't do 400rwhp on a 350 and an off the shelf Hyrdraulic Roller since last summer. I knew it was just a matter of time until someone posted this, but I am shocked at the small size of the cam and the TPI intake. Congratulations on what must have been a very pleasant suprise.

seawolf06

Congrats for sure. I'm going to be dynoing mine in april with an xfi Lt1 355. Your results are promising.

elementaltoad

im amazed by those numbers as well, even though you have aftermarket heads on it, can the stock 64cc iron heads have the valve guides machined enough to accept that size cam? im having a 383 built on the tpi platform but im keeping stock heads for now. so if you can get back to me before monday that would be awsome...if it can be done it would certainly liven up my 383 build.

89TramsAmGTA

I have not worked with improving the stock heads so I can't help. However the ones I have seen usually will accept a lift of .470". So you would need to increase the lift .100" plus a safety margin.