Hot 2.4S with small ports?

nabilious · 05-16-2006, 06:44 PM

I'm putting together what was a 2.2T and am using the 2.4 crank, S pistons and cyls (2.2 stuff, hi-comp.) and S cam but am using the original 2.2T heads. I was gonna have them ported and polished but their still smaller then true S stuff. Will this make it a more torquey motor? run outta breath on top? What can I expect?
Thanks,
Nabil

tadd · 05-16-2006, 08:28 PM

Kenikh and I have been picking this subject pretty clean of late (although we have been looking at 2.0s for him and 2.1 for me). The 'oldies' have posted some good stuff. Check it out.

In a nutshell, small ports choke off the upper end pushing the torque curve down. Most porsche cams are pretty mild in lift and don't need large ports. More lift seems to need more port. Small ports hurts bigger motors sooner than smaller ones. It is nice that the 2.2 heads have big valves, so the low end flow is taken care of by the factory for you.

I 'ported' some 2.2T heads to 38/38 with a bridgeport and an indexable boring tool - 38s naturally blend into the valve bowl real nicely. I would think that 36/36 should do nicely as well. It takes very little effort with a dremel to finish them off. I did all twelve ports in about 8 hours, and I only play a machinist on TV. It was another 8 or so to add a second spark plug once I wasted two heads getting the number correct.

Drop me a pm and I will be happy to email you a few pics if you are interested and any tips if you want to do the work yourself.

tadd

id911T · 05-17-2006, 01:14 PM

Will it make a difference having smaller ports with the S setup? Sure. Will it be a major issue? Probabaly not. The T heads don't flow quite as much as the S heads, but they aren't bad either, not like a single port Type 1 VW head. It'll be a bad@ss engine either way.

kenikh · 05-17-2006, 01:38 PM

Quote:

Originally posted by id911T
Will it make a difference having smaller ports with the S setup? Sure. Will it be a major issue? Probabaly not. The T heads don't flow quite as much as the S heads, but they aren't bad either, not like a single port Type 1 VW head. It'll be a bad@ss engine either way.

NOPE, no problem at all. I just tore down the motor of a highly respected PNW engine builder; it was a 2.4S pistoned and Solex cammed motor on 'T' ports. I think it pretty much speaks for itself.

Scott Clarke · Scott Clarke's Garage

I'd do a search using the term "E ports". There has been much discussion about the issue, but it has been a few years. John Luetjen has strong opinions about the mater and data to back it up. I would consult with him before you make a decision. I opted to enlarge my E ports for my 2.5SS with S ports based on what I read, and, believe me, I had other ways to spend my money. From what I understand, S cams with T ports give you the worst of both worlds: no bottom end and nothing up top. John claims that even S ports are a little undersized for applications like the 2.7 RS.
-Scott

nabilious · 05-17-2006, 08:29 PM

Maybe laying up on the cam a little (E or solex) might be helpful with stock ports. I'll take you up on that How-to Tadd, Thanks all.
Nabil

kenikh · 05-17-2006, 08:50 PM

I have never driven a car with them installed, but all I hear are rave reviews on the Solex cams.

jluetjen · jluetjen's Garage

Scott summed up my conclusions on this configuration fairly well. In a nutshell, I would expect an engine with 2.2T heads and S cams to run like an S below 3000 RPM (where you do a lot of around town driving), between 3500 and 5500 RPM it should run as well as an S, and then tail off. If you had S ports, the engine would be strong all the way up to 6500 RPM. If you take a look at the thread titled Camshaft Selection -- First Draft there is some head flow data as well as some other stuff that you might find helpful.