L head flow numbers

[Arkrider410]

Does anybody have to flow numbers for the l series heads

[datzenmike]

It's like a dyno. No two flow benches are the same. If you have a dyno that reads 5% higher than everyone else's, people will come to you for a tune up. I think most are home made and really the point is to show improvements in air flow, a before and after so to speak. Just because you have better flow does not mean it will make more power, it's just assumed it will.. it has potential to. For one thing an engine does not continuously draw air through it. It is a fast series of bites of air like a check out with people waiting then moving then waiting then moving. If I put an FIA head on my stock L20B is it going to magically make 200hp, of course not. There are many other factors in the mix. The intake might be restrictive or the carb (or carbs) and certainly the exhaust system might be restrictive. All these and more might not let a potentially good flowing head perform. Best you can do is have a head that isn't the choke point. Is adding more flow to an engine that is topped out really worth it?

 

L heads flow very well because of their design. The one with the largest valves and the largest ports presumably would have the potential to flow the best. Stock head? probably the U67. Imported stock head? probably the 219 or the re-issued 912. The A87 can be ported out to flow about the same but not in stock trim. The W58 could have the exhaust liners removed and would be pretty much the same as the U67 but for the round ports but then it wouldn't be stock would it. Worst flowing would be the 210 I would imagine.

 

So if comparing L heads you would have to compare them all on the same machine and in totally stock condition.... apples to apples. This would give you a base line for that head on that flow bench. Then if you unshroud the valves, use larger valves, higher lift cam, or port the intake or exhaust and there is an improvement you know you're headed in the right direction. It's a tool, an indicator.

 

 

Modified the title so that anyone looking for L head flow info can type this into our search engine and it will find this topic.

[Stoffregen Motorsports]

What's your ultimate question?

 

Are you trying to choose the best stock head? Or are you doing some port work?

[datzenmike]

If for goblin stick with the poor flowing 210 as any other head will drop the compression. Port match the intake and exhaust to the manifolds using a new gasket for the template. If having a valve job done anyway get larger valves and seats. be sure to specify the later hardened seats. I doubt the port runners are that thick so go easy 'hogging' out the ports. The closed chamber A87 head would be the next choice IF you have it milled down to regain the lost compression. It already has better valve size and ports. Avoid the U67 as this will drop your compression well into the 7s on an L16. To mill a stock U67 head down to get stock L16 compression, I calculate you would need to remove 1.3mm or 0.052'' from it and this will cause cam chain problems. 

 

When all this is done don't expect that much unless it is part of a comprehensive plan that includes a 'hotter' cam and 'better' induction.

[Arkrider410]

It is for goblin and I have an a87 head on a l16. I want to build a turbo engine out of it with l18 rods a 240 pistons.

[banzai510(hainz)]

if its pressurized does it matter that much. Of coase bigger is better, but if just a L 16 ,  turbo till it pops and then try another head

 

If I remember right those turbo grinds aint that much different than stock

[datzenmike]

That will take some doing as the bore will have to be opened up by 6mm or almost 1/4"!!!!!!! or 1/8" all the way round. Next the L18 rods will punch the KA pistons into the underside of the head by 32mm or over 1.25"!!!!!

[Stoffregen Motorsports]

He's probably taking about L24 240 pistons.

[datzenmike]

Good point. L18 rods are shorter by 3mm and although you are loosing 7cc of piston dish by getting flattops you are also gaining 16.22cc of combustion chamber for a net loss of 9cc. Plus the loss of at least another 3cc (if a closed chamber A87) Ah yes, 11 cc larger combustion chamber. Compression will be 7.75

 

If the A87 is an open chamber it's 7.4.

[datzenmike]

Keep the L16 rods and presumably L24 flattop pistons in a 2mm over bored L16 block. Compression would be...

 

9.7 with closed chamber A87 head

9.0 with open chamber A87 head.

[Arkrider410]

Question

Why the l24 pistons wont fit if it's bored 2mm over

[datzenmike]

Read again. It was made clear to me that you meant L24 pistons and not 240 (sx) pistons. Those won't fit for the reasons given.

 

 

It's right here. Does not say you can't use L24 flattop pistons.

 

Keep the L16 rods and presumably L24 flattop pistons in a 2mm over bored L16 block. Compression would be...

 

9.7 with closed chamber A87 head

9.0 with open chamber A87 head.

 

 

What I have said is that L18 rods would be a disaster for your compression ratio.

 

 

Good point. L18 rods are shorter by 3mm and although you are loosing 7cc of piston dish by getting flattops you are also gaining 16.22cc of combustion chamber for a net loss of 9cc. Plus the loss of at least another 3cc (if a closed chamber A87) Ah yes, 11 cc larger combustion chamber. Compression will be 7.75
 
If the A87 is an open chamber it's 7.4.

[Arkrider410]

But if it is turboed then the lower compression the better right

[datzenmike]

Some think so but it will run like a turd unless boosting. If extreme racing, with extreme boost there may be some efficiency gains with a lower compression, but if you are reasonable in your boost levels, plan carefully and limit heat induced detonation you can run what ever you like. Naturally the higher the compression the harder it is to control detonation withoout lowering the boost. If you use a cool air intake, an inter cooler, high(er) octane fuel, oil cooler, Al /H₂O injection, a more efficient cooling system, EGT and O₂ gauges some kind of detonation/timing control you should be alright. It isn't cheap boosting with the intent of making your engine last.

[Arkrider410]

Why would you bore 2mm

[datzenmike]

L16s are 83mm bore. L24 pistons are 85mm. Removing 1mm all the way round an L16's cylinders allows you to fit the larger L24 pistons. Besides the obvious increase in displacement to 1,672 (On the outside it will say L16 but inside it's almost an L17

engine) the L24 pistons are flat topped and have no dish. The compression will be higher and more efficient. 

[Arkrider410]

L24 has the same bore as a l16

L18 is 85mm

[bilzbobaggins]

where in georgia are you?   Just outta curiostiy?

[Arkrider410]

North of Rome south of Lafayette

[DISLEXICDIME]

I would use sr20det pistons

[datzenmike]

That would depend on the pin height. The SR has a pin width of 22mm and the L16 rod's small end takes a 21mm pin. The pin height of the SR is 32mm while the L16 is 38.1mm. A difference of just over 6mm. If you were to fit an over size 22mm piston pin into an L13 rod and then have the top edge of the SR piston milled down by about 0.6mm it would fit.

[Arkrider410]

I'm not going to use Sr pistons. As little machine work as necessary

[datzenmike]

If you are going to bother over boring 2mm on an L16 why not on an L20B? Take it to 87mm and swap a Z22 crank and pistons into it. Now you have basically made a 2.2 liter L20B. It will make about 115hp all day with out breaking a sweat and at 2.2 liters displacement and longer stroke, will have markedly improved low and mid range torque*. What would an L16 make? about 73 hp? Well 115hp is almost a 60% increase on power. And... we haven't even started messing around will cams or better carburetion. 

 

An L16 turbo making 115hp is going to be working pretty hard to do it on stock internal parts.

 

* A heavy truck need torque to move it. Torque is that sensation of a kick in the ass when you step on the gas. "There is no replacement for displacement"

[DISLEXICDIME]

If I was doing this I would use lz22 with l head and Sr pistons.

 

 

Now if I was doing a junk yard build I would use a l16 with a u67 head

[Arkrider410]

I don't want to overbore it that was your idea not mine.I know that a l18 or l20 would be better but I got to use what I got.