Sharpie Posted July 12, 2006 Share Posted July 12, 2006 If the head is removed to have valve stem seals replaced, what other works could be done at the same time ? I have some cams waiting to go in. I plan to go single long term so, keep this in-mind. Although, it will be a street car so, not a huge turbo. Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 12, 2006 Share Posted July 12, 2006 Weeeeellll..... If you have a lot of money to waste you could have multi-angle valve seats inserted and cut, and a port and polish job to improve airflow. It'll sound great when you talk about it down the pub and probably gain you a couple of hp at the wheels. Then when you go and stick a huge single on it, it won't matter anyway Seriously, you could replace the cam front seals and have the tappets re-shimmed. Might be worth investigating having the stems themselves replaced. Quote Link to comment Share on other sites More sharing options...
paul ashton Posted July 12, 2006 Share Posted July 12, 2006 Hit it with a heavy hammer,wake up and realise that you've got a soop. Quote Link to comment Share on other sites More sharing options...
Gamer Posted July 12, 2006 Share Posted July 12, 2006 Paint it Purple, the ladies love it. Quote Link to comment Share on other sites More sharing options...
paul ashton Posted July 12, 2006 Share Posted July 12, 2006 Paint it Purple, the ladies love it. You guys kill me. Quote Link to comment Share on other sites More sharing options...
Sharpie Posted July 12, 2006 Author Share Posted July 12, 2006 I'm glad I posted this in Technical Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 12, 2006 Share Posted July 12, 2006 It's a good time to do a general cleanup and optimisation of the ports. Remove any casting marks, that sort of thing. Keep the offset angles of the intakes. It can be DIYed if you have a bench, a dremel and spare time. Quote Link to comment Share on other sites More sharing options...
jagman Posted July 12, 2006 Share Posted July 12, 2006 Interesting Digsy that you consider it a waste of money to port/polish/cc/skim the head,surely if the point of fitting cams is to flow more air then why not allow the head to do the same?would not better flow through of air move heat out of the head,would not increase in flow/heat spool the turbo faster?the cc ing would make sure that each chamber gives similar power accross the engine,and a skim if necessary to ensure it is straight/true.multi angle valves may be of dubious value but the width of the seats could be of value.We often fit ported heads on the cooper s (supercharged) and show an increase of 32 bhp over stock,and an equal gain in torque,the head on gamers car was done and that seems to make good torque numbers Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 12, 2006 Share Posted July 12, 2006 I've found that a half-decent porting job will allow you to produce the same bhp at a couple of psi boost *less*. A good one will have even more effect. Quote Link to comment Share on other sites More sharing options...
jagman Posted July 12, 2006 Share Posted July 12, 2006 a couple of psi is a whole world of heat,I know the americans dont go a lot on porting the supra head but I dont understand why,once upon a time it was the starting point of any tuning ,yes factory heads are better but not perfect,I am a believer in treating the engine as if it is an air pump the more air through by any means = more power,just add fuel and in the case of the supra lots of it:d the by product being heat which tends to bugger everything it touches,its more complex than than this but this has always worked for me Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 12, 2006 Share Posted July 12, 2006 Interesting Digsy that you consider it a waste of money to port/polish/cc/skim the head,surely if the point of fitting cams is to flow more air then why not allow the head to do the same?would not better flow through of air move heat out of the head,would not increase in flow/heat spool the turbo faster?the cc ing would make sure that each chamber gives similar power accross the engine,and a skim if necessary to ensure it is straight/true.multi angle valves may be of dubious value but the width of the seats could be of value.We often fit ported heads on the cooper s (supercharged) and show an increase of 32 bhp over stock,and an equal gain in torque,the head on gamers car was done and that seems to make good torque numbers These heads you fit to the Coopers. Are you saying you get 32 extra hp just from porting and polishing? What % increase is that over stock? There's a difference between enlarging a port if it is overly restrictive and just polishing it out. There's even a school of thought that says a slightly rough port will flow air better than a completely smooth one. OK, to be fair, its difficult to see how porting and polishing could make things any worse, unless you go a bit mad with the windy-tool and end up adding permanant water injection but for the DIY-er I'd put it well in the "law of diminishing returns" territory. Quote Link to comment Share on other sites More sharing options...
dandan Posted July 13, 2006 Share Posted July 13, 2006 Our Cooper S made 163bhp dead on in stock trim. It then made 198bhp after the JCWorks conversion albeit the fuel was not just Optimax for the second run, there was a little 95 in there. That was a head and SC swap with the maps optimized once again - nothing too aggressive on the mapping front. I have my own school of thought on head modifications for the Supra which contradicts the common US (and seemingly UK) opinions. If you are planning to go for a decent single conversion then I would say there is definite merit in a good head guy with a flow bench working on the head. There is a definite "rule" of diminishing returns but that really relates to performance gain per £ and what you are willing to spend. Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 13, 2006 Share Posted July 13, 2006 Having seen the results you get with the stock 2JZ head in the real world - "the car is really fast and fun" - I'd say it's hard to justify porting and so forth unless you wanted to do it for the experience. I'm not knocking it, and it may well give some additional welly, but start at £350 + labour just to take the head off and put it back on again without doing anything else to it and it starts looking pricey. But then you could say that about body kits and stuff, so if you like the challenge or the feeling of a job well done or whatever, then port and polish away I like a clean engine bay, but all that elbow grease does a lot less for the power output than a port and polish, so hey -Ian Quote Link to comment Share on other sites More sharing options...
Lucifer Posted July 13, 2006 Share Posted July 13, 2006 If I were you I would get it all tested, 3 angle valve job, re lap the valves in, check guide clearences and be done with that. POrting and polishing on a Forced induction 2JZ will gain you about 0.02 HP per £ Quote Link to comment Share on other sites More sharing options...
b_have Posted July 13, 2006 Share Posted July 13, 2006 Very pleased with my head work from http://WWW.mkivstore.com. Was returned looking like new. Quote Link to comment Share on other sites More sharing options...
jagman Posted July 13, 2006 Share Posted July 13, 2006 The porting on the cooper s head alone gives about 16 hp the other 16 hp is from larger valves,but the original head is a poor design,the original post said the head was coming off anyway so the cost of removal is there anyway,what the exact gains are ported or unported are a bit of an unknown until someone does dyno testing pre/post porting I suppose only then bang for buck can be established,bear in mind the quantity of product already being sold with claims of power increase,and the troubles gone to in order to get more air into the engine ,surely the faster you can scavenge exhaust gasses the better. I dont really think a whole bank of gauges is good value for money who can look at them at full tilt,and engines fail despite having them. Dandan the works conversions are very costly for what they are ,the supercharger they replace is identicle and it only the pulley size that varies so you pay for a charger unnecessarily ,the head is only cnc machined at the outer edges of the port and not into the ports,valves/cam all remain stock,the manifold/exhaust combo is mild due noise constraints and the airbox only comes in after 4000 rpm but they sell the shit out of the conversions due warranty fears and very good marketing,they even offer upgraded injectors to 380 cc which we have tested at length and found NO benefits from except pub bragging rights! Badge engineering again ,the stock cooper s is 163/170 we often get 240-275 Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 13, 2006 Share Posted July 13, 2006 Agreed, re-shaping the port on a piss-poor design can give you some benefits. There are some truly terrible port designs out there - especially in the area where the valve seat and port blend into each other. I think the benefits you could expect to see from porting and polishing alone would become less and less when applied to more modern engines. Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 13, 2006 Share Posted July 13, 2006 Yes, true, the head was coming off anyway. I didn't mean to confuse the issue, but I think there is a big difference between doing some headwork while it's off anyway and taking it off specifically to do the headwork. And yes, OEM tuning packages are a ripoff, just look a the FQ-400 And use your Enter key more -Ian Quote Link to comment Share on other sites More sharing options...
Lucifer Posted July 13, 2006 Share Posted July 13, 2006 Well Said Digsy. As manufacturers are increasingly trying to get the last few bhp / economy figures out of their engines they have to dig that little deeper and pay attention to the smaller things like ports. Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 14, 2006 Share Posted July 14, 2006 Yeah, taking the head out just for porting is a waste of time. But if it already is out (like in this case) I think it's worth giving it some attention, especially since the valves will have to come out anyway. Usually people do the porting as part of a general rebuild, so it's hard to pin down the gains. I've done it after melted pistons or changing rings, so more than one parameters had changed at one time. But I remember in a friend's workshop a (rich) customer's turbobike had the head off just for porting (well he had a blown gasket, but replacing that wouldn't give any extra power) On the dyno it would show the same power at 2 psi less, which was quite impressive, since the head wasn't too bad to start with. Quote Link to comment Share on other sites More sharing options...
dandan Posted July 14, 2006 Share Posted July 14, 2006 Slightly OT so sorry for the hijack. 1. I've seen the two superchargers side by side are they are not identical, this was one of the first JCW conversions - not sure if the SC has changed since perhaps timed with the intro of the airbox/injectors? I'm not sure. 2. We did not have the airbox or injector upgrade. 3. Maintaining the warranty with the extra cost of the Works conversion has been worth every penny. To cut a long story short we had some head/head gasket related problems with the bill coming to just under £3000 - not a penny paid to BMW for the pleasure though That would not be the case with a non JCW conversion. Clutch and several related components have also been replaced under warranty - again would not be the case with a non warranted conversion. 4. I'd love to drive one making a genuine 270bhp - nice! Just my 0.02 worth. By the way, I agree if the 2JZ head is not off then it wouldn't be anywhere near my highest priority mod. If it is off (or if the exh manifold and intake is coming off anyway for whatever reason) then I would definitely pursue it. Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 14, 2006 Share Posted July 14, 2006 By the way, I agree if the 2JZ head is not off then it wouldn't be anywhere near my highest priority mod. If it is off (or if the exh manifold and intake is coming off anyway for whatever reason) then I would definitely pursue it. You'd grind the ports even with the head still on -Ian Quote Link to comment Share on other sites More sharing options...
dandan Posted July 14, 2006 Share Posted July 14, 2006 No, if the intake and exh manifolds were off and you were changing cams as well then to me it's no biggie to take the head off at that stage! (I see how my wording could have been taken a little differently though!!) What sort of an animal do you think I am!! Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 14, 2006 Share Posted July 14, 2006 Phew -Ian Quote Link to comment Share on other sites More sharing options...
Nic Posted July 15, 2006 Share Posted July 15, 2006 If the head is removed to have valve stem seals replaced, what other works could be done at the same time ? I have some cams waiting to go in. I plan to go single long term so, keep this in-mind. Although, it will be a street car so, not a huge turbo. CW overhauled my cylinder head a few years ago, here is the write up he did of the work he did. http://www.mkivsupra.net/vbb/showthread.php?t=2480 Quote Link to comment Share on other sites More sharing options...
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