Weissach1982

I have a 1982 Weiss. edition and i'm wanting to do a few mods to the motor. I have a few questions:One, are MSDS Headers (Ceramic) worth it? Two, will port and polishing along with a 3- angle valve job boost performance in the ole' 4.5L motor? And I will replace valve springs and head gaskests of course.

I already have the Nology Wires and test pipe, need a little more emphh and want to get my hands dirty, engine is 21 years old, its time to give it a bit more boost. Any ideas, opinions?

slate blue

I have been down this path myself, a lot can be done with your motor for not a lot of money. I had the heads analysed by one of our top head guys. He has state of the art equipment and loved the heads starting point. BTW you will need a five angle job. The other requirement is in the intake tubes.

Has your car a euro motor? with 300 hp? This is a critical factor, if it has don't bother with anything, you'll need to reinvent the wheel. If you do the heads and the exhaust are good places to start. Just remember you'll need to supply more fuel to feed your better breathing engine.

A dangerous lean condition may result in fatal engine damage.

I'll be making mandrel bent headers for LHD cars this year along with a H pipe. These will be ceramic coated inside and out. The first prototype header results can be viewed via the link below.(not equal lenght) these are made by myself.

<a href="http://www.momentoffame.com/snapshot.html?id=23548" target="_blank">Dyno graph</a>

I'm in the process of designing equal length headers now. I don't know if this is possible due to space constraints. Despite others claims I don't believe there to be a sets of commercially available headers that are equal length, and or are mandrel bent, from what I have seen these headers are pipe bent. There may be an exception with the Power broker's 180 degree header system. It seems quite well made and researched although it may be a little complex for some tastes.

I believe to get a good result from your engine you'll need a budget of about $3500. I hope that gives you something to think about.

Cheers Greg.

John Krawczyk

I'm just playing devils advocate here since i'm interested in this topic too. My heads have to come off for gasket replacments and i'd like to take care of some of those WYAIT projects.

Would'nt you need hotter cams to get any real benefit from all that head and exhaust work. (assuming a US spec engine). Also the US spec 16v motors have smaller valves. How does that impact all that other work too? What are the real gains (dollar/HP) from head work on US spec heads given that the stock valves and cams will be retained.

slate blue

Despite being down under I'm familiar with your engine, too many things need to be done just to get back to square one. The comp ratio is too low for hotter cams, the lower the comp the less scavenging, less power, simple really.

In the US you guys are in bit of a bind with low octane petrol, we have 98 octane commonly available here, and if you were to boost up your comp ratio to say 10.5 you would prbably get detonation problems. The precaution you could take against this is to have all the so called hot spots removed from your engine. This will give you a chance but it is still a gamble.

Basically I wouldn't touch that non euro motor, I would view other mods like dropping in a 4 valver as a cheaper option.

Cheers Greg

Jack '84 928s

YOu can use the 944 heads, and i think the cams for the 944 have better profiles but correct me if i am wrong <a href="http://www.devek.net" target="_blank">www.devek.net</a> sells them, thats what i want to do, and the have them ported and polished before they go on. The more i think about it the more money it will take lol.

Flint

Now, I have the Euro, 310 hp engine, PLUS I have higher performance cams. Or rather ONLY higher performance cams, the PO didn't do anything other than that (not even replaced the cheap-jack federalized cat). Would you say that is a good basis?

John Struthers

Weissach,
Don't do it.
While the Goldies' are underpowered compared to the all the 5.0L, 5.4L by at least 100 HP, we are down only by about 10 - 15 HP when compared to the 4.7L sHARKs. If you are really hungry you could shave the heads a little, just a hair mind you. Our compression ratio is 9.0:1, the 4.7L guy's are pushing 9.3:1. A slight shaving of the heads should put the 4.5L pretty close to the 4.7L engine HP output. Realise that you are reducing the CC size this should give you a little more real grunt -down low. Hopefully, -ask a head, and cam man- if there will be enough duration for evacuation and intake, Ithink the stock cam will be more than adequate.
You may have to experiment with advance, too.
If you shave the heads though, heat, detonation, gasket sealing problems, and a whispered promise that if our 4.5L engines are'nt interference engines they probably will be after the shave'.
There are enough money pits on the planet without digging a new hole.
A few prices:
Euro Head -1 each, you need two- used $500.00
Not sure if they are bare or not. Bare most likely.
$1000.00 for heads.
Euro cam, left, used $650.00.
Euro cam, right, used, $650.00
Intake valve, 8 each @$35.00 = $280.00
Exaust valve, 8 each @ $45.00 = $360.00
Hydraulic lifters, used, 16 each @$20.00 =$320.00
Hydraulic lifters, new, 16 each @$65.00 =$1040.00
then there is the gaskets, studs, keepers, springs, seals, locators....
So, just whats listed above runs you from:
$3260.00 to $3980.00.
A used 4.7L from 928 INTL', if available, runs around $3500.00.
But, that puppy may need a EURO COMPUTER to run correctly. $$$$
Keep what you have...save your bucks for an S4, GT, GTS.

Weissach1982

alrighty, thanks guys. Speaking of newer 928s, I'm looking for an S4 but not right now. I'm just curious to know which one is the best, which options, performance, etc.
Thanks

Flint

I don't know if you care about keeping your car in perfect condition, but as you have a "limited edition" wouldn't performance upgrades take away from eventual value? Admittedly, "value" on these may take awhile, but that may be an issue to you.

ViribusUnits

If you keep the car, resell value don't mean a thing.

And resell value don't mean a thing to me. Yea, like anyone's gonna belive a 83 with GTS bumpers is origional...

Now to the point of the post, I know for sure that you wouldn't need a euro computer, beause the pre 84 Euro's didn't have a computer. ;-) Now if you want the S2, you've gotta go get the 84-86 Euro computer.

Good luck on the modifications, I'm watching!

slate blue

Hi to Fletch who sent me a private email, basically Fletch asked two questions, one about wheels and offsets, if I could direct you to my early post on the subject and if you have further question about that please post them on the board as I don't get on the board as regulary anymore. There are plenty of photos for you.

<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=14;t=002433" target="_blank">Eighteen inch wheels</a>

Your other question relating to modifying your two valve motor,

"I am also interested in doing some mild head work along with Stage 2
Headers and exhaust from Devek and I have a couple of questions.
I have a shop locally that does great work but what do they need to
know...5 angle valve job? Could the heads be shaved for a slight increase in compression ratio (we have 91 for premium) stock car will run on 87. The car only has 54k on it and motor is strong so I don't want to get into the bottom end.
Hope to hear from you soon - Darren Fletcher"

I see your problem in not wanting to touch the bottom end, the later euro motors had a 10.4 comp ratio. Let's deal with this first, the higher the comp ratio, the more power you get. So you want as much comp. as possible without getting detonation. By removing hotspots in the combustion chamber, such as machining ridges and carbon build up, you can alleviate this somewhat.

The 5 angle valve job is simply 3 cuts to the valve and 2 to the seat. BTW a 2 valve car will not be able to run as high a comp ratio as a 4 valve as the exhaust in the 2 valve engine gets hotter, it is only marginal though. There is also a better combustion chamber design in the 4 valvers.

I was quoted to do my heads $2000 AUD conversion is .060cents to a dollar so about $1200 USD and that was by a fellow with state of the art equipment and thirty years experience in racing. The heads would also be reconditioned at the same time, that was included in the price and the reason I raise that it is critical that the valve height is correct.

Please speak to Devek about their headers, but I would think that level one would be adequate as you engine may go backwards with those bigger pipes. I think that the 3 inch single exhaust that Devek sells could be good for you. I have access to plenty of euro motor parts, at very cheap prices, I don't know if they will ship O/S but if you were serious I would ask. I myself have a spare set of euro cams, they need a slight grind then renitride.

Now with 944 heads on the 928, I know this is possible, but from my knowledge of these engines you need the 944 cam boxes and heads of course, these have to have a water jacket mod. but the most expensive item would be the special camshafts, the 944 has different valve spacing, so as such the 944 has different lobe spacing on the camshaft.

I'll take a break now, let me know if that answers your question.

Erik - Denmark

Greg,
Interesting talk - Can you please explain what you mean with:

'By removing hotspots in the combustion chamber, such as machining ridges and carbon build up, you can alleviate this somewhat'

And how to discover and remove this hotspots?

slate blue

Sure Erik, the machining ridges are what is left when the raw casting is machined for things such as the valve seats. The other accepted thing to do is in relation to keep detonation to a minium is to have a tight piston to head clearance.

Our 2 valve heads are state of the art for 2 valve heads as far as combustion chamber design goes. I.E. quench area. What I don't know is how close the piston comes to the head on the early engines and US spec motors. These engines BTW are almost one in the same. E.G both use the smaller intake runners, both have identical valve sizes, and similiar if not identical comp ratios. As a point of interest the later euro 4.5 liter is generally believed to put out about 270 hp and not the 240 which Porsche claims. This engine has has compresion 10 to 1 versus 8.5 to 1. I saw an interesting article in a magazine. It was very well conducted and what it measured was how much power difference there was with diferent comp ratios. They changed the comp ratio from 8 to 1 to 9 to 1 to 10 to 1 to 11 to 1 and measured the power diference in hp and torque all the way through. It also detailed how the engine note changed and how the idle was efected, the camminess of the motor is decreased with higher comp. It was very enlightning.

Another note to get more power from the 2 valve euro motor, maybe others, but the tubes analysed were my larger euro intake runners, is to grind out the restriction near the injector. The tube from memory is 40 mm in diameter and the tube closes down to 33 mm, my head guy had a shocked look on his face when he saw it. "Well we'll have to fix that." he said. Then we were going to hone them. There is a place in Melbourne which does honing for about half the price in the States.

The other I should have mentioned about the head job was, the flow should be maximized from the point where the valve first cracks open, do not concentrate on peak flow numbers, but area under the curve or your car will run like a dog.

Hope this helps.
<img border="0" title="" alt="[Eek!]" src="eek.gif" />

Fastest928

We have both 1.5/8" and 1.3/4" headers for all 928s! Plus full exhausts for all years.

We have done heads for 928 up to 709 hp in a big engine and also have the 944 heads at bargin prices.

I have a euro CIS 310 hp engine for sale at $4000 including cis system. If anyone want it, email me.

Marc
DEVEK

Fletcher

Marc, how much for your heads? 84s car us spec.

P.S. any dyno specs for my motor w/stage 2 headers and exhaust. Mild head work can't hurt either heh!!