I've got a 383/cc306 with stock ported heads similar to LE2 style porting and the intake is already port matched to the heads. I was either going to port the stock 52mm bores for the TB to 58mm myself or send it off to AI and get the whole thing redone. My question is if I do this is it realy worth the $325 plus shipping to get it done? I do have plans for about a 250 shot of N20 in the near future.

Also my MAP drops off to 90 kPa above 5800 rpm and was wondering if i could be getting valve float or if it was a lack of air due to the 52mm TB I have on there now. I have read where folks with similar result have attributed those symptoms to valve float and if that is so I would switch from the Comp Lifters I have now and get the new GM style. Springs are comp 986's w/1.6 Pro Mag rockers all seat pressures and heights where checked.

Thanks fellas!

 

As far as the nitrous goes, they say a 200 shot is about the max you can go on a LT1 intake due to the way they flow. Anything over that go direct port.

If you have the extra money, have it ported. It couldn't hurt....

 

987's are a problem

 

Lloyd Elliot ports the intakes for $200.00 or so.
He took material out of the plenum and the runners and opened the holes to 58mm. The overall job is excellent.

 

If you really have that much vacume, then get your intake ported and look at a different cold air intake. Step up to a 58mm TB too. 90 is pretty bad.

Ai does a good job with the intake.

As for the valve float, it might be a combination of the lifters and the spings. Give Aia call and they can set you up with everything you need.

 

I have 986 spring not 987 and how could that be a problem? Please explain.

Also I will get in touch with Lloyd and see what he does with the intake. Obviously my set up flows insane it's just the fact that the MAP drops thus I'm going to the 58mm. I am slightly worried about valve float but that is unlikely. Yes it could be a problem with my CAI I'm not realy sure. What I'm more concerned about is the intakes capability to handle a large shot of nitrous and if intake deburing and shaving metal from the plenium is in fact going to help the a 250 to 300 shot in the future. Some folks have shot a 300 shot on a LT1 intake with a wet system and made it work but I'm not sure what modifications if any they did to the intake.

Keep the suggestions coming fellas..........thanks!

 

I had the huge drop off of the map readings too, at the dyno on friday. I have a 385, AI heads cam intake, and the ws.6 ram air. I took the filter off while dynoing and I didn't loose nearly as much. So, Im gonna scrap the ws.6 ram air and put the CIA back on and do some datalogging. I have a 58mm TB also. Put down 438rwhp and 431rwtq. So, I know there is a couple HP left on the table, I have to figure out how to keep the pressure up in the manifold.

AI does an excellent job on the intake porting, I highly recomend it! I did it, and my motor runs ****, and makes huge power, as you can see.

Hope this helps a bit.