Acura TL Builder

Alrighty fellers,

Which set of heads are better for a Type-S J35?

Ive read tell that J32 heads where superior because they either flowed better(Somehow), or changed compression.

The Type-S cams would be preferred over the Acura RL/Odyssey of the same years. This is because in the case horsepower is preferred over Torque.

I’m a noob at this and there are many experts that know this engine very well that are welcome to chime in.

csmeance

aren't J35 valves larger than J32? If yes larger valves+better flow... but why stop there and just go with the J37A1 heads which will flow way better anyway and work easily.

justnspace

iTrader: (1)

common sense!

Acura TL Builder

So use the ported 3.2L heads for the Comptech, and port n’ polish the J35 heads when the engine is built.

justnspace

iTrader: (1)

just do what Gerz did and use the j32a2 from the 2nd gen TL. lol

Acura TL Builder

Doesn't seem to be common sense.

How much would it really help? The cast headers will flow.

oraclem20

IIRC it's either no difference, or 1mm on the exhaust valves. Some difference yes, however the main difference in the heads is the volume on the exhaust side of the heads and the quality of finished work. Ported (lightly) 32a3 heads will do about what a 35a8 head will do. I have no comparison to a 37A1 head in that scale however, maybe Thisaznboi can chime in here as I think he's used one as well as Gerzand
Yes. As long as the exhaust areas are ported well, the ported 3.2 heads should do fine. Switching to a PnP j35a8 head after though will allow you to see gains with minimal tuning changes except turning things up.[/QUOTE]

This, this is the only option for full high boost flow out of our heads due to the single exit design in the latter years. I will be testing the limits of a 32a2 head myself as I've been waiting to do this for years and finally will have the apparatus and means. The main reason theorized as to why we can't go high boost without breaking piston ring lands is that the exhaust gasses simply cannot escape the head efficiently on outer cylinders because they have to pass through 10" of exhaust head path before reaching the exhaust where the center pistons only need 4". This massive difference sends exhaust gasses everywhere, bouncing off closed valves, going into other cylinders, rebounding back into the cylinder etc. to a much higher degree than on a traditional headered setup. The j32a2 head is the last head compatible with these engines capable of using headers, one tube per cylinder, with equal length exits, which is what you need in high HP builds that can send an exhaust pulse all the way through the exhaust and back twice before the next cylinder opens due to volume of compressed energy. In addition when under boost, smaller volume passages are more efficient at delivering energy as long as they're shaped correctly, so you lose less energy pressurizing air that isn't in the cylinder and the limitation of these smaller exits is foregone by the extra PSI forcing air through the passage. As long as that passage doesn't rebound the air in a negative way (single exit heads, looking at you) the smaller volume heads actually make it easier for boost gains.

I'll be porting my 32a3 heads, then looking into 32a2 heads to port, not 35a8. a2 heads also allows custom tuning of header lengths per cylinder, which could allow a biturbo setup to be used, or biturbo twincharged (one turbo per bank that's fairly large and kicks in around 4000/vtec lobe activation rpm, and a SC to get you to that point in the RPM range quickly, 800 hp build). Right now we're stuck at around 600 hp max because the exhaust ports keep blowing up the pistons with hot air. Fix the header/single exit problem, high HP is possible on J series. I'm going to try and avoid it initially by using tons of w/m to bring down CC temperatures and cool the piston every stroke in addition to cooling the charge. Only one way to find out.

Acura TL Builder

Thanks for the insightful post!

csmeance

This, this is the only option for full high boost flow out of our heads due to the single exit design in the latter years. I will be testing the limits of a 32a2 head myself as I've been waiting to do this for years and finally will have the apparatus and means. The main reason theorized as to why we can't go high boost without breaking piston ring lands is that the exhaust gasses simply cannot escape the head efficiently on outer cylinders because they have to pass through 10" of exhaust head path before reaching the exhaust where the center pistons only need 4". This massive difference sends exhaust gasses everywhere, bouncing off closed valves, going into other cylinders, rebounding back into the cylinder etc. to a much higher degree than on a traditional headered setup. The j32a2 head is the last head compatible with these engines capable of using headers, one tube per cylinder, with equal length exits, which is what you need in high HP builds that can send an exhaust pulse all the way through the exhaust and back twice before the next cylinder opens due to volume of compressed energy. In addition when under boost, smaller volume passages are more efficient at delivering energy as long as they're shaped correctly, so you lose less energy pressurizing air that isn't in the cylinder and the limitation of these smaller exits is foregone by the extra PSI forcing air through the passage. As long as that passage doesn't rebound the air in a negative way (single exit heads, looking at you) the smaller volume heads actually make it easier for boost gains.

I'll be porting my 32a3 heads, then looking into 32a2 heads to port, not 35a8. a2 heads also allows custom tuning of header lengths per cylinder, which could allow a biturbo setup to be used, or biturbo twincharged (one turbo per bank that's fairly large and kicks in around 4000/vtec lobe activation rpm, and a SC to get you to that point in the RPM range quickly, 800 hp build). Right now we're stuck at around 600 hp max because the exhaust ports keep blowing up the pistons with hot air. Fix the header/single exit problem, high HP is possible on J series. I'm going to try and avoid it initially by using tons of w/m to bring down CC temperatures and cool the piston every stroke in addition to cooling the charge. Only one way to find out.[/QUOTE]

Some guy over russia came out with a "magic" exhaust design for right after the header on single exit J-series. He said something about using venturi to get the exhaust out with his special way and wanted like 5K for his "custom" turbo mount piping.

teh CL

iTrader: (1)

I've always been curious what the J37 Dual Vtec heads would do, boost or NA.

oraclem20

Some guy over russia came out with a "magic" exhaust design for right after the header on single exit J-series. He said something about using venturi to get the exhaust out with his special way and wanted like 5K for his "custom" turbo mount piping.[/QUOTE]
Any further info on this from anyone? There is a principle of venturi that can increase exit velocity and cause local gas scavenging to prevent rebounding the air. I had wondered about it myself but lack the physics knowledge to originate the entire theory. Modifying it into reality from concept however, that's within my grasp.

Cutting the side off of a j37A1 head and welding a plate across came up as an idea too, although I'm not sure about how extensive those welds would need to be to hold turbo exhaust gasses and expansions.