I have a n/a block w 951 oil housing and wish to install a 1 piece OPRV. I purchased a good used unit and cannot seem to install it into the housing. I have removed/installed the 3 piece unit a couple times. Is there a difference in the units, a early and a late 1 piece OPRV specific for early blocks?

 

Someone correct me if I'm wrong, but if you want to use a 1 piece OPRV, you need a housing that came with a 1 piece OPRV.

 

Actually you can use any year 951 or NA housing but the OPRV itself has to match the block series. If you are using an 86 or earlier block you need the 1-piece conversion type. Anything after 86 to some early 87's you need the later type 1-piece OPRV. Look at the length and seal placement.

83-86 1-piece conversion OPRV



87+ standard OPRV

 

Understand, I'll have to buy a new conversion one because the one I have (if I remember) is actually longer than the 3 piece one...

 

How can you tell it is longer when the 3-piece type isn't assembled when out of the oil cooler housing? Compare the pics above or get the date off your block to be sure.

 

Steve,
Just going from what I remember from last week at the shop, I recall insterting it into the housing and the 1 piece OPRV did not go all the way in, Dia. difference?

 

Thanks for clearing up my confusion Steve!

 

The early blocks took the shorter conversion OPRV and had a removable sleeve the old piston slid against (do not remove!). Sounds like you have an early block and late OPRV. I would still check the date on the block and compare your OPRV to the pics because those things are very expensive.

 

Steve,
I purchased this complete race motor from a competitior that had it rebuilt by a porsche race shop. The engine had been run and had the 951 housing on it. I will look into this a little closer but the housing accepts my 3 piece unit and slides in the sleeve in the block smooth. I assumed this engine builder would have had this built for a 3 piece but maybe not after all. thanks for you help!

 

if it has a 3 piece then its an 86 or earlier block- from 87+ they only used the one piece unless its some freak circumstance. In this case you need the conversion one piece that only fits the early cars-86 turbos. I need one as well so let me know if you find a good supplier. paragon-products has them for $280 each or so.

 

Sounds like you have the wrong oprv / housing combinatoin

 

Actually the housings do swap between early/late blocks so it shouldn't matter in his case as long as he has an early 1-piece conversion OPRV. Tom McGuinn posted some great info on this awhile back.

https://rennlist.com/forums/showthre...highlight=OPRV

 

yeah i have an s2 housing and cooler on my car- 91- and my car is an 86- i just used the three piece unit for now. I need the early one piece soon though.

 

I might have a pre-87 1-piece conversion OPRV. I havent pulled it off from a spare damaged 951 motor yet but it looks like one from outside. I can check tonight if either of you are interested.

 

If I decide to use my 3 piece OPRV is there seal(s) needed. the unit looks different from the new one and cannot tell if there is an o-ring to be installed.