FRporscheman

I'm about to start building a 951 motor. I've been doing research for over a year, a lot of reading, asking, and looking around to learn everything I can about these engines, and I've learned a lot. Well now I finally have the time to start putting parts together, and I'm not sure which of the popular tricks I actually need.

I want a reliable engine. At the same time though, I don't want to do a whole bunch of work to the engine that I really don't need. I want to build the best engine that's in my budget... which is why I have turned away from 3.0L for now and "settled" on 2.5L.

I want about 325-350hp at the crank, and it will be driven on the street. It will be my occasional road trip car, and probably my commute car half the time. I might do some DEs again in the future, but that's not really what I have in mind for this car. What I have is a completely disassembled '86 951 engine, and I plan on reusing the stock RARST rods and pistons. And a new stock Sachs clutch.

So these are all the things I've heard about and I'm not sure if I actually need for a medium-performance 2.5L engine.:

ARP head studs
cometic head gasket
machining the block deck
deck plate or pegs
cross-drilled crank
knife-edged crank
balanced reciprocating mass
crank scraper
I'm sure I missed somethings

I wanted your opinions on what things are overkill for the street, what things are a complete and absolute must, and any in-betweens? Thanks!

PorscheDoc

IMHO, value wise, all of those are overkill for a street motor that is only putting down 325 crank hp.

carlege

Your gonna have one hell of a motor. if thats what your putting in it.

MM951

325bhp is nothing on a well sorted 951..

Duke

I agree with Doc. None of these things are needed for what you are looking for.
I would start with a good rebuild and use the saved money on a small ball bearing turbo plus the needed supporting tuning parts such as exhaust, injectors, wastegate and MAF.
With your power goals you could have an ultimate spooling machine which is super nice for a full street car.

V2Rocket

http://www.lindseyracing.com/LR/Parts/951PACK300.html

blown 944

I agree with Duke, rebuild as stock and spend the $$ on a DBB turbo, MAF, exhaust, and clutch.

Maybe even opt for a 6 speed.

With a quick spool these cars are quite fun.

V2Rocket

overkill, but my how solid it will be lol

arash.
right now youre saying "im looking for 350hp" but thats not going to be true once you get there. all youll want is more more more

you might as well sell your 44, a 968, your mbz, your house and drop out of slo because this is what they call 'the slippery slope' in 951-ish

Chris White

ARP head studs - not really needed - bu tif you are going to remove the stock ones then you might as well use the ARP
cometic head gasket - not needed
machining the block deck - Yes
deck plate or pegs - No
cross-drilled crank - No
knife-edged crank - Maybe -it will get the engine to rev quicker - but an Alum flywheel is cheaper!
balanced reciprocating mass - always
crank scraper - only if you are going to track it.

billthe3

Depending upon how long you want the engine to last and how well-broken in the engine is, you may want to get the cylinders bored out and go with some slightly oversized pistons so that you don't have to deal with excessive blowby issues if you decide to mess with higher boost levels. That is the only problem I'm having with my engine, but aside from that I pulled 280hp/300tq whp with an o-ringed head, widefire gasket and 5 angle valve job from lindsey. I've done more stuff since then so I'm sure I'm making more power now, and I am not at all afraid of the stock block breaking or anything. The only issue I have is that I'm getting a somewhat high amount of oil consumption/blowby, but I have over 100k mi now on the engine.

Also, for a street car, I personally decided to not bother with a lightweight flywheel because I didn't want to deal with the lack of torque when initially launching from a stop.

Tom M'Guinn

I'd replace the studs if rebuilding -- though stock or raceware would also work fine.

Widefire head gasket should be fine.

Spend money on good block work -- do the deck and bores by all means -- give the pistons to the machine shop so they can size bores accordingly, and use only use a proven 944 machinist -- trust me on that!

Have valves and head surface done too, along with con rods

I'd confirm specs, then polish and cross-drill the crank, but not knife edge

Balance by all means

xsboost90

let me put it this way-my engine is dead stock from cambox to oil pan but refreshed- stock header and crossover, all bolt on turbo, exhaust, wastegate etc... 359rwhp with Maxchip stuff and now w/ the Vitesse stuff im sure i can see 400rwhp no problem w/ some tuning.

theedge

I would not bother with knife edge crank IMHO. Get a KEP Stage 2 pressure plate or even Stage 1, and a lightened stock flywheel.

Andy1212

Yup. 325 is easily attainable with just bolt ons. But i would look into a garrett ball bearing turbo. you will get a much better power delivery at 325 then with a kkk/borg warner.

Own Goal

My engine is mostly together but not in the chassis yet. Was in same boat with about same goals. I also spent a lot of time reading and talking with the guys on here. This has to be THE place for the 951 knowledge base. My original goal was a 300-325 or so rwhp street weekend fun car. Set your goals and pay attention to the stuff guys on here have to sell. I've gotten only good stuff at fair prices. I scored so far (I'm done) 3" exhaust, aluminum flywheel, Tial 38mm, adjustable FP regulator, stainless fuel lines, 55# injectors and a LOT of good advice. You will also get to meet and get great advice from the vendors that support this site. Lindsey, John Vitesse, Paragon (Jason), Speed Force (Tim); all good guys willing to help.
As for the long block I went stock crank but all Race Ware blots on the bottom end, new stock Porsche head studs, coated bearings, steel sleeved with coated stock pistons, surfaced block, and head and all balanced. Went with a stock Sachs PP and an aftermarket 930 disk from Zimms here local. Should hold fine, I hope. Using custom midsized turbo but did spring for the full Vitesse setup. Got a bit carried away toward the end of the deal so potential for upper 3's is there which wasn't in the original plan. I'm thinking my default then will be with minimum boost (7 #Tial internal springs) and a hot setup like 14-15# with matching map. Actually I might have default de-tuned to like way low. I have two teen sons and neither will be on the insurance or have key access. Never know.