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hp gain of 531?

box car racer

New member
Joined
Oct 19, 2003
Location
Where beer flows like wine
Alright, I have read a bunch of post about the 531 and none of them have any hard numbers of hp gain from as compared to the other heads. I have a 1990 744ti that I am in the process of doing the following:

16t turbo set a 15 psi
MSnS
3" turbo back
cold air intake
hotter cam(a, vx, or ipd turbo cam)

I really have two questions: what is the hp gain (if any) on a stock motor vs. the 530 head? Will there be enough hp gain with my planned modifications to justify spending the money on having one shipped over or would my money be better spent porting my 530? I'm just trying to be smart with my money.

Thanks,
Jeremy
 
hmm... hard numbers are tough because it really depends on the set up. I'd say if you find one cheap from someone parting a penta engine then go for it- otherwise I would clean up a 530 and do a big valve head or a header or something depending on your goals.
IMO the big port head is worth about 20-30hp at 1 bar on a standard b23ft. Just my (almost random) number based on what Pat's engine made on the dyno with his 405.
 
At some point, the small exhaust flow becomes a problem. It is the same as that of any Volvo head. Generally on a turbo, you want to increase exhaust flow. Volvo did not do that when it turbocharged the cars. It just added sodium to the exhaust valve to handle the extra heat.

I am not sure it is the best idea to use a stock 405 or 531 head on a high boost motor. You'll make more power, but you will stress the exhaust valves more and heat them up and eventually that could cause problems.

I would use one with larger exhaust valves and seats. It would be cheaper since you could leave the intake alone -- it already flows pretty well (about as well as a worked normal head).

Philip Bradley
 
pbonsalb said:
I would use one with larger exhaust valves and seats. It would be cheaper since you could leave the intake alone -- it already flows pretty well (about as well as a worked normal head).

Philip Bradley
Roughly how much would it cost to get larger exhaust valves on my 531? Would it be wise to do that (if I have the money) before I go ahead and put this thing on my car? Should I worry about porting/polishing the exhaust ports to aid in flow? I guess it would also be very very wise to add a 90+ manifold to this combination too eh? Hell while I'm at it I should get a B21NA intake and add some injector bungs. Then slap that whole new top end onto my engine. Sooon.

But yeah, how much for exhaust valves and the labor to install?

John
 
"But yeah, how much for exhaust valves and the labor to install?"

that would depend on what valves you buy and who installs them bro. :p
The r-sport valve kit from sam with intakes, exhausts, and springs is about 350 us iirc. I would get new seats and new bronze guides as well.
I'd guess in canuck bucks maybe 600ish to get it done right. There's no real in between, I'd either do that or just clean up the exhaust side (ie pocket port). My 531 is getting the r-sport valve treatment with new seats and bronze guides and a porting by me. My old ported scp 398 with stock valves was more than enough to destroy torque rods and such though. Just some thoughts to chew on.
 
Green Death said:
Weird. what head did the 95-98 940 turbos have then?
i do beleive 530's

531's are on the B230ET with A cam is was fazed out just before the CAT law cam into force in 92, and B230FB NA engine with VX cam
 
Green Death said:
"But yeah, how much for exhaust valves and the labor to install?"

that would depend on what valves you buy and who installs them bro. :p
The r-sport valve kit from sam with intakes, exhausts, and springs is about 350 us iirc. I would get new seats and new bronze guides as well.
I'd guess in canuck bucks maybe 600ish to get it done right. There's no real in between, I'd either do that or just clean up the exhaust side (ie pocket port).
$600 is WAY more than I'm willing to spend. I'd much rather spend my money elsewhere on the engine, and just clean up the 531 a little bit. Maybe we should hook up some time and you can give me a few pointers on how to port this thing properly?

Thanks,

John
 
ya for sure. hey I will soon be set up to retrofit piston oil squirters to b23's if you are interested as well.
 
If you wanted a great performance head, a 531 with the intake ports, intake valves, and combustion chambers pretty much left alone, and just exhaust valves in the 38.5 to 40.5 mm range with larger seats to match would be the way to go. Custom exhaust valves run about $30 each. Times 4 is $120. The seats might cost half that, but that much again in labor to press them in. A multiangle valve job on all 8 valves would cost maybe $25 per valve. Some port and bowl work on the exhaust side to match up the larger valves would cost probably $25 per port. OEM springs are fine unless you are doing really dramatic things. It would be easy to spend $600, but you would have a great performance head when used with a performance cam.

I would not even think about just dropping a used head on the motor. I would definitely have it rebuilt. Bronze valve guides or at least inserts are cheap and most used heads have worn valve guides. On a turbo, you will lose oil through worn guides. Oil in the combustion chamber does not help with detonation.

Philip Bradley
 
pbonsalb said:
A multiangle valve job on all 8 valves
if you look at stealthFTI's site, he states his reasons against going multi-angle on the exhaust seats is the fact that heat transferance to the head is the only way the exhaust valves have of shedding heat from the exhaust gases. intake valves are cooled by the incoming air charge but exhaust valves dont have this.

no doing a multiangle job onthem you cut out on some of the valve to head contact area that they have so cuting down on the ammount of heat that is able to be transfered
 
On more stock setup there's probably something to that but I would think that in this case a new seat, larger diameter valve, and especially a bronze guide would offset that.
 
Go with a factory valve job, then. While I have not surveyed all the performance machine shops in the country, I have not found one among those I have surveyed that believes an OEM valve job is better than a multiangle valve job. Some prefer 3 to 5, some prefer so many that there aren't really any angles -- which is sort of the direction a 5 is going in.

There is nothing wrong with stock. It works for most people. When you start modifying, there are usually risks and compromises. Factory stock is a pretty good balance of those risks and compromises. If you want to move away from stock, you have to reassess them.

There are many different routes to higher performance. I have seen the flow numbers for multiangle valve jobs, for porting, and for bigger intake and exhaust valves and have seen them for the stock counterparts. If you have another way to get the same performance increase that you prefer for whatever reason, that is fine. I am pretty sure that at some point if you continue in your quest for greater power, you will reconsider multiangle valve jobs.

Philip Bradley
 
While there are specifications for seat width, generally wider for exhaust, and even wider for turbo, there is a tendancy for seats to get too wide as they are cut. The only way to narrow them again is by cutting additional angles, which will also help flow.
The tricky part is how wide and where those additional angles are going to be.

And that is the tip of the iceberg.
 
i wasn't quesioning there performance benifit, what i was talking about it exhaust valve longivity

to copy a section from his site at http://www.pbase.com/image/25727557

"The exhaust seat is wider than the intake seat. Because the exhaust valve runs a lot hotter than the intake valve. The seat conducts heat away from the valve head when the valve is closed. The wider seat helps conduct more heat.

To the learned eye, it is obvious that I did NOT do a "three angle valve job". Even though such a three angle grinding of the seats might improve the flow a little bit, I am more interested in making sure that there is sufficient metal there to conduct the heat away from the valve head and into the casting....and do it uniformly. After looking at four different heads with cracks between the seats, I will do all I can to minimize any heat overload; or any non-uniformity in heat transfer.

I lap the valves in to end up with valve seats that are on the high half of allowable widths: so the valve heads can shed heat better. I do not remove any more material from the valve seat inserts so that they can have the best chance of remaining stable and located; and not become a hot spot.

Increasing flow via camshaft change is the way to get more flow without sacrificing durability. A larger and more efficient turbo will also help.

The valves and seats are the hottest things in the combustion chamber. The intake valve is cooled by the incoming air/fuel mix; in conjunction with the valve seat. Reducing the heat transfer via the seat only puts more heat into the incoming air: that does not help performance. The exhaust valve head is cooled primarily via the seat face contact. Reducing the heat transfer by narrowing the contact surface area elevates the valve head temperature; and that could become a source of preignition.

Those are the reasons I consider a three angle valve job to be a false economy on a boosted motor. " BY StealthFTI


now to me this makes alot of sense in the keeping you motor running for a long time instead of developing great power for a short ammount of time.
 
I understood.
I just cut to the chase, maybe left out details.
The wider exhaust seat is to transfer more heat, and the reason for an even wider turbo exhaust seat.

But if it gets too wide it has low spring pessure for the area being sealed. That can lead to sealing problems and even longevity issues.
 
Don't forget..

The turbo motor has sodium filled valves which have the sodium inside to cool the head
and conduct heat up the stem and probably into the valve guide would be my thought. I understand Stealthfti's approach and think it's a good one but I wanted more flow and with
sodium valves you have a big benefit for removing heat.
Best regards,
 
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