head work or bottom end?

jakes_hachiroku
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head work or bottom end?

Postby jakes_hachiroku » Thu Jan 18, 2018 5:07 am

so this is more just a conversation starter but would really like to know what you guys think! so IFFFFF you had to only chose one, which would you benefit from most? working the head ie. cams, cnc port and polish, valve springs and stuff like that. orrr working the block, ie. forged pistons, rods, stroker, bore the cylinders, you know. to keep this controlled this will be lets say a standard 16v smallport keeping it N/A. so what do you guys think?!

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Re: head work or bottom end?

Postby mr2mk1hero » Thu Jan 18, 2018 5:44 am

I'm really no expert when compared to some of the guys on this forum, but I think working on the block and working on the head really go hand in hand and separating them is weird. A lot of compression without the right cams makes no sense, just like aggressive cams with stock compression also don't make sense. But let's assume it's for the purpose of having a fun conversation and throwing theories out there, which is also ok I guess :) In which category does the head gasket fall? Head or block work? I'll assume it's the head since it's a HEAD gasket.

Soooo....If I had to choose I would focus on the head and get a thin head gasket in there to raise the compression. With some aggressive cams, the appropriate valve springs and a well ported head you could get a revvy responsive screamer that comes alive at the top of the rpm range which for me personally is more fun to drive than a high torque stroker that pulls strong from low rpms. But I have to say it would be a shame to simply ignore the block.
Also, an engine with a lot invested in the head would also benefit a more from improvements to the intake (itbs or mabye bike carbs?) and exhaust (custom manifold, downpipe, etc.), which I think is less true from an engine where the head was completely ignored? Someone correct me if I'm wrong.
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Re: head work or bottom end?

Postby jakes_hachiroku » Thu Jan 18, 2018 5:48 am

yea its a tough one because like you said its silly to go nuts on the head and have stock bottom end lol and vise versa! but I do agree about a nice revvy 4age that screams to 9000 rpm haha

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Re: head work or bottom end?

Postby Gino1X1 » Thu Jan 18, 2018 12:16 pm

As mr2mk1hero wrote, by this time (after 25~30years of manufacture) it's really unthinkable to do work on them separately. But okay, for discussion purposes by either/or I would say Head!! Like, mild cams and their corresponding valve springs like lift up to ~8.1mm and total advertised dur. of 272degrees. And yes, a thin headgasket, equalized head porting and cleanup, matched-to the-head-porting of the intake manifold with the bluetop's throttle body or by the same token the 240SX's KA24DE one. About 140bhp with a good torque curve.

Or else just turbo the poor thing to 8psi, good exhaust system and a good standalone and have a phantastic day. :-D

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jakes_hachiroku
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Re: head work or bottom end?

Postby jakes_hachiroku » Thu Jan 18, 2018 12:22 pm

Gino1X1 wrote:As mr2mk1hero wrote, by this time (after 25~30years of manufacture) it's really unthinkable to do work on them separately. But okay, for discussion purposes by either/or I would say Head!! Like, mild cams and their corresponding valve springs like lift up to ~8.1mm and total advertised dur. of 272degrees. And yes, a thin headgasket, equalized head porting and cleanup, matched-to the-head-porting of the intake manifold with the bluetop's throttle body or by the same token the 240SX's KA24DE one. About 140bhp with a good torque curve.

Or else just turbo the poor thing to 8psi, good exhaust system and a good standalone and have a phantastic day. :-D


yea I thought this was gunna turn into people leaning towards the head work lolol def wouldn't go any bigger that 272 and 8.1 cams (exactly what im running in my smallport now haha)

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Re: head work or bottom end?

Postby oldeskewltoy » Fri Jan 19, 2018 10:17 am

smallport n/a

There is no reason to spend BIG $$ on the bottom end... it does need more piston(compression)... and the internals could be lighter... BUT @ 10.3:1 you are already pretty good there, plus the addition of a metal gasket(ASSUMING blocks deck is perfect) bumps that higher....

If n/a smallport - a fully ported head, a set of Catcams 252 duration 8.5mm lift cams, along with a set of adjustable timing pulleys - and you should be @ about 140-150 whp (170-175@ the flywheel)
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Re: head work or bottom end?

Postby sirdeuce » Sun Jan 21, 2018 7:46 pm

Headwork! Just know the limitations of the bottom end. No sense in building a top end to destroy the bottom end. Typically, the bottom end can handle 9000rpm with the weak link being the oil pump. My current engine is running 8500rpm limiter with a totally stock bottom( yeah it bounces a lot and I can't wait for it to go bad, that would motivate me to get my built engine in). I've had this running like this for a couple of years now. If you have the early 40mm crank you can build some awesome engines without issue and the 42mm can be taken a bit further. Either can spin 9000 easily enough.
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Re: head work or bottom end?

Postby jakes_hachiroku » Mon Jan 22, 2018 8:38 am

sirdeuce wrote:Headwork! Just know the limitations of the bottom end. No sense in building a top end to destroy the bottom end. Typically, the bottom end can handle 9000rpm with the weak link being the oil pump. My current engine is running 8500rpm limiter with a totally stock bottom( yeah it bounces a lot and I can't wait for it to go bad, that would motivate me to get my built engine in). I've had this running like this for a couple of years now. If you have the early 40mm crank you can build some awesome engines without issue and the 42mm can be taken a bit further. Either can spin 9000 easily enough.

yea head work keeps coming out the victor on this one! lol yea my drift set up right now is a 3 rib block bored 1mm over with some 89 mr2 pistons and some forged rods and the smaller 40mm crank. head is a smallport with 272/8.1 lift cams and two weber 40mm carbs and I have the msd rev limit set to 8 to keep it safe lolol

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Re: head work or bottom end?

Postby sirdeuce » Mon Jan 22, 2018 10:21 am

With the 272 cams I'd kick the limit to 8500. IF you were to go the other way, block, I'd say put the funds into a 7A block and build a 7AGE. Not as rev happy but the torque increase is worth it. If you were to go this direction a light flywheel and rods will help with the "sluggishness" most complain about with the heavier 7A bits. Staying with your set-up though, I'd look for a 7 rib block and keep the lighter crank.
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Re: head work or bottom end?

Postby jakes_hachiroku » Mon Jan 22, 2018 11:02 am

sirdeuce wrote:With the 272 cams I'd kick the limit to 8500. IF you were to go the other way, block, I'd say put the funds into a 7A block and build a 7AGE. Not as rev happy but the torque increase is worth it. If you were to go this direction a light flywheel and rods will help with the "sluggishness" most complain about with the heavier 7A bits. Staying with your set-up though, I'd look for a 7 rib block and keep the lighter crank.


do you think I will see more out of the cams by letting it rev that little bit more in drift?

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Re: head work or bottom end?

Postby oldeskewltoy » Mon Jan 22, 2018 6:29 pm

jakes_hachiroku wrote:
sirdeuce wrote:Headwork! Just know the limitations of the bottom end. No sense in building a top end to destroy the bottom end. Typically, the bottom end can handle 9000rpm with the weak link being the oil pump. My current engine is running 8500rpm limiter with a totally stock bottom( yeah it bounces a lot and I can't wait for it to go bad, that would motivate me to get my built engine in). I've had this running like this for a couple of years now. If you have the early 40mm crank you can build some awesome engines without issue and the 42mm can be taken a bit further. Either can spin 9000 easily enough.

yea head work keeps coming out the victor on this one! lol yea my drift set up right now is a 3 rib block bored 1mm over with some 89 mr2 pistons and some forged rods and the smaller 40mm crank. head is a smallport with 272/8.1 lift cams and two weber 40mm carbs and I have the msd rev limit set to 8 to keep it safe lolol



89 4AGE is still 9.4:1... STRONGLY recommend you bump compression in this engine... especially with long duration cams
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

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Re: head work or bottom end?

Postby jakes_hachiroku » Tue Jan 23, 2018 10:03 am

oldeskewltoy wrote:
jakes_hachiroku wrote:
sirdeuce wrote:Headwork! Just know the limitations of the bottom end. No sense in building a top end to destroy the bottom end. Typically, the bottom end can handle 9000rpm with the weak link being the oil pump. My current engine is running 8500rpm limiter with a totally stock bottom( yeah it bounces a lot and I can't wait for it to go bad, that would motivate me to get my built engine in). I've had this running like this for a couple of years now. If you have the early 40mm crank you can build some awesome engines without issue and the 42mm can be taken a bit further. Either can spin 9000 easily enough.

yea head work keeps coming out the victor on this one! lol yea my drift set up right now is a 3 rib block bored 1mm over with some 89 mr2 pistons and some forged rods and the smaller 40mm crank. head is a smallport with 272/8.1 lift cams and two weber 40mm carbs and I have the msd rev limit set to 8 to keep it safe lolol



89 4AGE is still 9.4:1... STRONGLY recommend you bump compression in this engine... especially with long duration cams


so with the smallport head that im running what would be some "oem" pistons I could pick up for cheap with floating wrist pin that would be higher compression?

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oldeskewltoy
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Re: head work or bottom end?

Postby oldeskewltoy » Tue Jan 23, 2018 4:54 pm

std bore?

DNJ P927 pistons, along with Honda Prelude rings. Should run about $125 for both.

oversize bore gets tougher.... but can be done
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

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Re: head work or bottom end?

Postby jakes_hachiroku » Wed Jan 24, 2018 5:18 am

oldeskewltoy wrote:std bore?

DNJ P927 pistons, along with Honda Prelude rings. Should run about $125 for both.

oversize bore gets tougher.... but can be done

yea I am 1mm over for the cylinders... 82mm lol

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oldeskewltoy
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Re: head work or bottom end?

Postby oldeskewltoy » Wed Jan 24, 2018 6:52 am

not sure of cost.......

http://www.perfectengine.com/Rock_P927_ ... c-p927.htm - use pulldown menu for size options

http://www.perfectengine.com/Hastings_2 ... 2c4684.htm - use pulldown menu for size options
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

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Re: head work or bottom end?

Postby mad_86 » Mon Jun 11, 2018 6:57 pm

Head work! Doo head work! Lol

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