Josh B

I figured while I had the head off to fix my bent valves I should modify it some I had a few 2.7 liter 47mm intake valves on the shelf and so I went down to the local machine shop. They put slightly bigger seats into the head. The stock turbo intake valves are 45mm and the stock turbo intake throat is 40mm. With the new seats I have just under a 42mm throat. I am going from a area of 1257 sq mm to 1385 sq mm. That is about a 10% increase in intake throat area. From the pictures I've seen I think that is slightly smaller than what folks are getting with the larger chevy valve swap out.

I didn't have the head bench tested as their fee to do a before and after adds up quick. They charged $250 to put in the new seats and smooth out the throat area. I was short one valve and that was $140 new from Sunset. I still have to have the head re-assembled and that will probably be another $150.

Here are some pics. To the left and in the back is my 1000 mile head I have as a backup in case this doesn't work out real well For reference sake I will be running a Super 61/#8 hotside, 55lb injectors, Vitesse MAF/chips/piggy back, 3 bar FPR and SFR 3" exhaust. Also this head was already o-ringed and lightly ported/polished before I took it in.

ilikemy944

Can't wait to see the final result!

potent951turbo

+1

You always know a picture from Josh, the part is always incredibly clean and they are always on his hardwood floors lol

aribop

Looks great! Can't wait until it's back together.

carreracoupe997

Josh, is this the car from Road Atlanta?

samluke

It woud be interesting to know the flow comparison of a stock 951 head, to this approach, and then the 2.7NA head. All results with the same stock cam/valve lift. It would also be nice to know the same on the exhaust side ie 951 with ceramic ports versus the 2.7NA.

The 2.7 NA head is supposed to be a major improvement over the 951 head, it would be nice to know factual comparisons.

My request is a tad selfish as I have a 2.7NA head and had planned a 3.0 Turbo 968. Now I am not sure what I am going to do, and I would like to know independently how good a 2.7NA head is. It may influence my next decisions.

333pg333

Agreed. Thanks for the write up Josh.

carreracoupe997

Josh, run a n/a cam on a 951 like I do. 3 degrees more duration on the exhaust. Breathes better and keeps her spooled.

ilikemy944

I think a different cam is going in as well... :P

Josh B

Chuckle - I was out in the rain on my covered back porch talking on the cell phone to Albert and scrubbing that head with purple power in anticipation of these pics Then I brought it inside and dried it off on the couch in my lap while my wife looked on semi mortified Made sense to me.

Hey Steve - yup - I am afraid it is. She should be back up and running by the end of next week though.

I know - I was trying to envision a cheap flow tester with a vacuum cleaner turned around to blow. Maybe using some lexan from Home depot and some sort of tube with a ping pong ball in it. The higher the ping pong ball floated then the more flow?

Probably should just take some brewskies over to that machine shop and see if they would let me play with their flow bench on a friday evening

That is a good idea! I have a Web-Cam from Lindsey - that grind #247 - that I put into the cam tower while I had it off. According to their website it has .480 lift, 254 duration, 234 duration @.050. Not sure how that differs from a stock turbo cam or compares to the NA cam.

Josh B

Finally eh?

333pg333

Some info in here about our cams.

http://members.rennlist.com/951_racerx/