Looking for some advice on IM choice. My specs are as follows

Dart short deck block 85mm
Eagle crank and rods 89mm
wiseco 12:1 pistons
Ported ITR head
toda valvetrain
skunk2 Pro 1 cams
RMF narrow
2.5 header back
Victor x manifold
Edelbrock 65mm TB

I currently have , what i believe to be, a velocity problem. The car seems to be flat til 7300 where it comes alive till about 9100. This does not work well with my pro 1 cams. Mainly because I am looking for more linear power and not peak dyno numbers. I chose the pro 1's for this reason. I think the victor x is the culprit. I am considering a ITR intake manifold and a 67-70 mm TB. Any advice would be appreciated. Especially from those that have had a similar dilemma.

 

That manifold is made for large engines and high RPM. Do you have a dyno graph of this engine? Is the engine tuned?

 

No graph, Mild tune just street tuned with wideband. Cam gears still at zero intake and exhaust. Any suggestions? manifold was a last minute choice based on some opinions of the motor being 2.0 and around 12.3 cr

 

wont a larger TB just slow down velocity..

 

Dump the Victor X and get a ported ITR IM. Those cams will want to be dialed in as well-0,0 is not ideal.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by toekneevwj &raquo;</TD></TR><TR><TD CLASS="quote">wont a larger TB just slow down velocity..</TD></TR></TABLE>

Velocity is unique to each engine. A large engine with good ring seal and a short rod can afford a bigger throttle body because its more acute pressure drop on the intake stroke vs a smaller motor with a long rod. RPM comes into play somewhere in there, too.

 

The victor x is designed to make power from 7-10k....probably would have been better off with the performer x or a ported type r.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">

Velocity is unique to each engine. A large engine with good ring seal and a short rod can afford a bigger throttle body because its more acute pressure drop on the intake stroke vs a smaller motor with a long rod. RPM comes into play somewhere in there, too.</TD></TR></TABLE>

Yes, I agree. I was talking about in general. I didn’t want the guy to run out and buy a 70mm TB thinking that it will solve his problem.

 

I was only considering a larger TB with a smaller plenum. That way the air passage is long enough to fill the plenum but the runner length and size to build velocity. Am I thinking correctly? What size TB with ported ITR manifold?

 

if you get a type r have it ported and your throttle body port matched to the mani. If you send it to MaxBore, he can do it all and also will taper the tbody down which will help speed up the air velocity.
another option to do the porting is JGE. he cuts the plenum off and ports the runners then welds it back together.
or you could get a type r replica (aebs, skunk2, performer x?, probably others) where the type r design was taken into account and slightly, or attempted to be, improved on. You probably wouldn't need to have it ported for your setup and you could just get your tbody port matched.