head work, Who has done it and what kind of performance comes from it?

[Gordon15734]

Taking a look around at doing some head work to my engine to get better performance. What price range and performance, and ways to get more out of my engine?!?
Thanks everyone!

[guru944]

Gordon15734:

The 951 head because if the ceramic Lining on the exhaust ports is rather difficult to modify. Also of the Sodium gas filled Exhaust valves. Most shops & machinist will Port/modify the Intake side and replace needed parts on the exhaust side. It will be very pricey to get that kind of work done on that side.

Lindsey and a few others have also done these heads and may provide more clarity otherwise.

Later...

[nize]

bigger intake valves can be done. not many can do it properly. read this thread:
http://forums.pelicanparts.com/porsche-944-turbo-turbo-s/482147-big-valve-head.html

[Paulyy]

Lindsey racing have a price range and what they do with their gains. I'd say go to them.

If you have a stock turbo and not planning to swap it. don't bother, you won't really see much gain worth the money.

[333pg333]

Originally Posted by nize

bigger intake valves can be done. not many can do it properly. read this thread:
http://forums.pelicanparts.com/porsche-944-turbo-turbo-s/482147-big-valve-head.html

Have to say that 40-60whp at lower boost levels just by increasing the valve size might be a tad optimistic Peter?

[nize]

to match the larger valves, the entire length of the intake port on the head is made larger in diameter as well.

other locals who have had the same work done have before/after dynos that show the difference.

i haven't dyno'd mine but you can definitely tell the difference.

[guru944]

Gordon:

Have some custom race valves coming next week for a Customer. I'll post pics once i get them....

Later.

[guru944]

Gordon15734:

"Hot of the Press" Custom Blue-printed Stainless Steel Competition Valves for 944 NA & 951 applications.
Each valve provides a 8% flow increase & no special valve springs or retainers needed. Proper Cylinder head Port work would improve flow even more but a flow bench would be required & locally available. Rev up to 8k safely.

Same valves on my CS and Race car and a few local project vehicles so far...

PM me your questions for your present or future project builds. Later...

, , , ,

[nize]

is the exhaust valve sodium filled? if not, how does it handle the punishing exhaust heat in a turbo application?

[guru944]

Nize:

The older oem Porsche sodium filled valves were made of a different allow and hollow and filled with sodium for improved heat transfer such that the valves would not break and keep them cooler above 900'F.
The newer Stainless Steel alloy valves provide strength, cool better and longevity to the valve train system Turbo or non turbo. There are no issues at all. Cost is ~40 to 50% less and easier to obtain and manufacture.

These are Quality Controlled ISO 9001/9002 manufactured custom pieces made in the USA.


PM me if needed.

Later...

[guru944]

Update:
1 st order on way to Germany, 2.5L Valves Intake & Exhaust. Thanks Henry.
2 nd order is pending for 2.7L Intake valves. Thanx Brad.

Later.

*Copied*

[guru944]

Why are these valves improve performance?
The valves are undercut at throat and provide a swirl Flow towards the edges of the valve. That promotes Improved fuel atomization, Intake stroke cooling and Better air distribution within the cylinder before beginning of ignition/combustion stroke. A real 8% increase in flow just by swapping out valves. No need for cams.
Weight is ~ the same or lighter.
I have been using the same valves for years. Since 2001 NIRA/NDRA/NHRA race season. Go to my site and see the work and parts installed on both my 944S and Conquest TSI.
" No Jedi mind trick, remember"
Later... **copied from my original press release post**

[commdiver]

I would definitely use a trusted known Porsche 944 knowledged shop as any increase or modification in volume to the intake runners of a head will warrant velocity changes. Speed of air coming into engine is key and you want to keep that up. So remember flow rate doesn't tell the whole story and it's never about just 1 thing it's about the whole package, so attitude of (air pump) engine can change not necessarily for the good unless you design the entire air path to work together from entry to exit.

[guru944]

Commdiver:

Yes, your point is well presented & taken.

Not everyone here can have a very technical background or can be a semi pro-race driver & consultant for more than 10 yrs or have the equipment or techniques to do research or test, measure, quantify and analyze theory, lab/dyno/flow bench and field application data results good or bad.

It is well documented in all 8 of my reference books including page 110 of Cartech book: Engine Blueprinting or HP Books: Engine Airflow pg 92 (see pix below).
That Stock valves can usually benefit from a practice called back cutting with a 10% or better improvement in low & medium lift flow with no loss in maximum lift, by eliminating sharp edges under heads which disrupt airflow.

Fact: No other port modification are needed to see these improvements.

Let's face it "Racing is research" Technique is key.
"Form follows function". Proper planning yields positive results. The best leaders come from the best servants in their service or ministry.

[333pg333]

Ideally you'd want a way to control your air / fuel mixtures with a potential 8% change up top.

[guru944]

Patrick:

Yes, the 1986 and all Motronic DME's (2.0 or later) are adaptive and a self learning engine management system (see pix below pg 33, Motronic Systems, Pulse Injection-Theory; Book: Bosch Fuel Injection & Engine Management 1991). They should make the proper timing fuel and ignition adjustments with a proper working oxygen, air temp, coolant temp and air flow metering sensors with the gains which are really throughout the rpm band, not just peak. All the 944/968 DME's include FQS programmable selective settings which are also available for user base setting tune-ability.
Bare in mind, a MAF air flow sensor conversion (Rogue Tuning or others) also allows for increased nonrestrictive airflow (+6 to 12%) which makes also noticeable difference in performance by delivering air flow volume and cooler air temps for combustion and the Motronic DME with the MAF configuration mapping will also make the proper correlative adaptive adjustments.
Usually a 20% increase in any engines performance will demand more custom base tuning for overall drive-ability, power and economy.





Hope this sheds more light on doing the SS custom valve upgrades, later...

[DannoXYZ]

Uh no. Look at every single chip on the DME board and you'll see that there is no re-writeable storage of any kind. This has been verified ad-naseaum with datalogging which shows no changes to injector or ignition timing between different runs. The only thing that changes the pre-programmed stored base-map values is engine/air-temp sensor and O2-sensor feedback in real-time. Those changes are not cummulative and is not stored anywhere. There is an error in that book in that the authors got earlier Motronic ML3.1 mixed up with the later Motronic M3.1 which does have storage.

Here's what I've done on head-work, if you're gonna do it, don't do halfway-solutions:

1. 2-4mm bigger valves with narrower stems (new guides & seals), lighter than stock by 15-20%

2. back-cut heads

3. fully-contoured variable-radius valve-seats. Think 7-angle is better than 3-angle or 5-angle? How about 50-angles, 100-angles? Curved seat gives much, much better flow at any given valve-lift. And the different curvatures match the different flow-patterns around the valve. The side that's closest to the cylinder-wall needs a different curve for best-flow. The side that's next to the other valve needs a different radius than the area's that 90-degrees away.

4. beryllium valve-seats has much, much faster heat-transfer than any other material.

5. full D-porting of intake-tract from valve-seat all the way to plenum. Be very, very careful to match the port cross-section at the manifold-to-head intersection. Use the gasket as a template to match both sides.

6. tear-drop the valve-guide where it protrudges into the intake

7. cam-profile to match all the above. Needs longer duration on both intake & exhaust, more overlap and later intake-closing. This flattens out the torque-curve so it's flatter and doesn't drop 20-30% of your max-torque by redline.

8. long-tube headers, 4-1. Flattens torque-curve and holds max-torque to redline. Broadfoot-racing has one.


It all really comes down to what performance-specs you want and budget.

[333pg333]

The only thing I’d add to that is that you will find different hp and tq curves on standard 2.5 capacity motors than you will on larger bore 3L motors. I’m talking 8v in this case. Even by going with larger valves you will run out of flow on a large bore 3L or bigger motor. So while your hp and tq will go up, you will hit a wall at about 6k rpms and both curves will tail off steadily. This has been verified by a number of us. I am running over 500whp (real hp not show queen rubbish) on a highly modified 3.1L 8v motor in a racecar with virtually everything improved. The only thing we haven’t changed at this stage is a stock (extruded honed) intake. It does have a larger 66mm T-body. We’re pretty happy to have the performance we have currently and don’t want to shift the curve further across to the RHS for longevity even though a larger plenum, shorter runner intake would be an overall improvement over stock.

[medicineman3245]

I have a racing head and matching intake manifold from my former race engine. Work was done by Circle Performance. Can send specs sheet.

[RKT951]

I have a level 3 head from Lindsey, no flow numbers as claimed. I got all new Ferrea valves and had the head flow tested then CNC ported with a increase of 28 CFM over the LINDSEY port job in Tucson AZ so if anyone wants a quality port done intake only. Nice to not get ripped off by LR