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Bigger valves and better cam
by
Hoble
on 04 Feb, 2013 16:53
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I'm building a 1.6/1.9 franken motor with power goals of 250+ hp. The block is all but assembled. now i need to deal with the head. Im about to order a new 1.9 head from overland in California. I have a dr. diesel cam for it but im thinking its not enough. was planning on doing some port and polishing as well. The head is where you can gain a lot of power if done right and if you can cram enough air in, so i was now im thinking bigger valves and a way more aggressive cam. Ive only heard about the dr. diesel one for the idi motors but ive heard of people running tdi cams? any benifit of running a tdi performance cam?
I dont know where to start with the head. Havent delt with them before. Some advice would help me along greatly and would be much appreciated!
Lee
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#1
by
8v-of-fury
on 04 Feb, 2013 17:06
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I am pretty certain the Dr. Diesel camshaft is the best you can get for the 4 cylinder Volkswagen IDI.
250 horsepower, crank or wheel? Steep goals either way
I cannot for the life of me remember what his username was, but he was a serious/heavy builder of these 1.6 engines and the most he managed was 195 BHP with one done to the nines.
You are correct in the thoughts of cramming air in, but as far as I am aware the 1.9 head is pretty damn optimal as-is maybe some port work needed.. Get a really efficient turbo, and an Air-to-Water intercooler with an extremely efficient setup so you will experience less than 0.1% of pressure drop through it and it will be able to cool to ambient temps. This will allow you to run as much boost as whatever turbo you decide to run will run efficiently..
This is where the real power is, lotsa fuel, and lotsa cold air.
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#2
by
Hoble
on 04 Feb, 2013 17:30
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block it bored out 1mm over with ks pistons, rosten rods, lighten intermediate shaft, compound turbos (gt2056 and gt2871 the 2871 will more than accommodate me air needs) water meth, water air IC, cam, head work, giles super pump, rebuilt injectors, 3/8ths block girdle, gravity feed fueling.
What ever i can do i am. I'm avoiding propane and nos though...
You are correct though, 250 (wheel btw) is going to be a challenge, thats the point haha
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#3
by
theman53
on 04 Feb, 2013 18:53
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I will PM you. I have a head being made that maybe similar to what you seek.
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#4
by
rabbid79
on 04 Feb, 2013 19:40
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but ive heard of people running tdi cams? any benifit of running a tdi performance cam?
That's interesting you should say that. I've heard of the TDI guys using IDI cams for more power.
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#5
by
RabbitJockey
on 04 Feb, 2013 19:55
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I am pretty certain the Dr. Diesel camshaft is the best you can get for the 4 cylinder Volkswagen IDI.
250 horsepower, crank or wheel? Steep goals either way
I cannot for the life of me remember what his username was, but he was a serious/heavy builder of these 1.6 engines and the most he managed was 195 BHP with one done to the nines.
You are correct in the thoughts of cramming air in, but as far as I am aware the 1.9 head is pretty damn optimal as-is maybe some port work needed.. Get a really efficient turbo, and an Air-to-Water intercooler with an extremely efficient setup so you will experience less than 0.1% of pressure drop through it and it will be able to cool to ambient temps. This will allow you to run as much boost as whatever turbo you decide to run will run efficiently..
This is where the real power is, lotsa fuel, and lotsa cold air.
Dave's engine did 195whp 935racer. But he also was very short on fuel since he only had a 9mm pump and could have used a better turbo since he was running a to4e. Even still 250 is alot to ask of a 1.6 but I don't think it's impossible. 1.9 heads can definitely use porting, they have the same ***ty exhaust ports as a 1.6
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#6
by
rallydiesel
on 04 Feb, 2013 20:38
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Bigger exhaust valves would definitely help. Just be careful of the porting as there are coolant passages close to the exhaust ports near the manifold end.
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#7
by
R.O.R-2.0
on 04 Feb, 2013 22:38
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Bigger exhaust valves would definitely help. Just be careful of the porting as there are coolant passages close to the exhaust ports near the manifold end.
are the VALVES, or the PORTS the weak point?
i would think that opening up the ports would make for bigger gains than just bigger valves..
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#8
by
mystery3
on 04 Feb, 2013 23:54
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IIRC one of the crazy Scandinavian guys: Aki76, I'm blanking on the other names to look up, had an IDI head with huge valves in it, it looked like the intake and exhaust valves practically touched one another. Might be worth searching and digging through some old threads.
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#9
by
Blocksmith
on 05 Feb, 2013 04:30
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IIRC one of the crazy Scandinavian guys: Aki76, I'm blanking on the other names to look up, had an IDI head with huge valves in it, it looked like the intake and exhaust valves practically touched one another. Might be worth searching and digging through some old threads.
Yeah, pretty sure that was an Aki76 build. I think the valves were titanium, iirc. TurboJ, Alcaid, and MJF are all names to be aware of if you need to read about making big power.
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#10
by
Aki-76
on 05 Feb, 2013 09:04
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some flowbench data
blue graph is from almost stock head
red graph is from a head that has bigger valves and which has been extensively modified
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#11
by
theman53
on 05 Feb, 2013 18:08
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From all that I have read and done the valves are huge gains and porting are big gains. You should have both, but if you can afford valves that is where the big gains are. 7mm stems too not 8mm. Porting is all about velocity, not all out flow, so remember that when you are thinking of taking tons of material out.
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#12
by
Hoble
on 05 Feb, 2013 20:10
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As for the porting, I know gas motors you are supposed to leave the intake a little rough and not polish that one, only the exhaust side. Does this not apply to diesels? Polished would help air get in fast.
And 7mm stems on a 1.9 head?
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#13
by
theman53
on 05 Feb, 2013 20:28
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7mm if you can find guides and valves
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#14
by
rabbid79
on 05 Feb, 2013 21:10
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As for the porting, I know gas motors you are supposed to leave the intake a little rough and not polish that one, only the exhaust side. Does this not apply to diesels? Polished would help air get in fast.
And 7mm stems on a 1.9 head?
I'm not sure polishing is an issue here, since a diesel doesn't rely the rough surfaces in the intake/port to help mix the fuel and air the way a gas engine does. I think you would be fine with polished surfaces.