Smoothing the intake

[Guest Anonymous]

I picked up an 82' motor (with a P90 head) and am about to jump in and clean the hell out of it. I also picked up a new hone (for five bucks) that is small enough to fit the entire intake (throttle & runners). Would it be a good idea to smooth that baby out, or leave it alone. No other mods will be done for now. There will be injector upgrades (Merc. 450cc) and ignition, but any future changes will be made down the road as money becomes available.

 

Also, on my 77' would I have to enlarge my fuel lines to drop this motor in?

 

Tell me what you think is best.

 

Nic

[Lockjaw]

You will not have to enlarge you fuel lines until you get really wild with the power output.

 

I don't know about honing the intake. I think there are humps and stuff in there that would probably tear up the stones on the hone, unless you have one with the little balls on it. I think I would be inclined to leave well enough alone. IMO.

[SleeperZ]

I've heard the same thing on the fuel rail - it's good for 300+ hp. I am using an N42 intake on my turbo, and the tool that really helped smooth out the bumps and port the intake (60mm tb) was a 1" drum sander on my drill. Costs about $5 including replacement sandpaper drums and it won't clog up - just cuts like crazy until it wears out. Of course it wont reach the bumps waaaaay inside.

[Tony240ZT]

Can someone verify the size of the Mercedes 450SL injectors, I hear all sorts of different sizes. I've heard 370cc/min 390cc/min 420cc/min and now 450cc/min?

 

I have them installed in my car (`73 w/L24ET), they are too big for my application. I think I'll be going with 370cc/min. I *THINK* the Mercedes injectors are 420cc/min.

[Guest Anonymous]

I'm sure your right. My list of sites that have info are gone, so my numbers might be WAY off.

 

All I know is they install with ease.

 

Thankx's all for the great posts!

 

Nic

[Guest Anonymous]

If it's any help I know for a fact that it is a BIG no no to smoth out the inside of a conventional carb intake. The reason is that the roughness of the casting actually helps the atomization of air and fuel as it goes into the heads. On a dry manifold type system the more air you can get the better however be careful not to disturb the airflow charactheristics or you might have some fun problems. I can't see where you could really hurt it but I'd say pull it down and find out what the iside looks like first.

[Guest Anonymous]

Got2B has a point about a wet intake, if my concept of port/polishing for fuel-injected intakes (dry extraction) is right, the idea is to reduce the amount of aerodynamic drag to a minimum while keeping air velocities high- i.e. smoothness, correct runner sizing and port matching are key. For my '77 (log indiv. runner style) intake I plan on doing a home port match to the p90 head and to a larger 65mm t/b, and lightly smoothing things out. In my mind the most effective way to increase VE for the stock turbo system would be a better cam, at least for latter rpms. Now I know its hard to beat the stock turbo cam duration and lift, but if I find that the motor stops breathing at 5000 rpms .. that will be one of the first things to tweak.

$.02 deposited.

-980mak

[Guest Anonymous]

Those are great tips, thankx the both of you.

 

I sure am ganna check out the intake and get a better understanding of the flow dynamics. I have to wait a few weeks though, my garage space is occupied by a freind and he will be moving into his new house (and out of mine) very soon. Then the fun will begin.

 

Nic