4GAE tuning for fast road use

[firstmk1]

In the past 'discussions' a few have said they want to talk about serious NA tuning for the 4AGE. I'll soon be rebuilding my engine to get the best out of the throttle bodies and cams that I ran before the old bearings died.

I've read a number of books for background information, studied engineering (automotive biased) and run a tuned engine so I'd like some technical chat, if you're up for it?

What modifications have people tried? Did it work?

My spec:
288 deg cams (lift details not to hand)
Individual throttle bodies
54psi fuel pressure
Lightweight flywheel
Crank balanced (with flywheel, clutch and pulley fitted)
Forged rod with new standard pistons
Block cleaned, checked and re-bored...fitting for knock sensor added
Haltech E6K ECU

I've also got a set of uprated valve springs that may be needed to go to high RPM, not sure yet.

[cartledge_uk]

My spec:
288 deg cams (lift details not to hand)
Individual throttle bodies
54psi fuel pressure
Lightweight flywheel
Crank balanced (with flywheel, clutch and pulley fitted)
Forged rod with new standard pistons
Block cleaned, checked and re-bored...fitting for knock sensor added
Haltech E6K ECU

I've also got a set of uprated valve springs that may be needed to go to high RPM, not sure yet.

Very nice list!

I thought that uprated valve springs weren't just for high rpm, but to prevent/resist spring squish with larger profile cams?

[dex]

I thought that uprated valve springs weren't just for high rpm, but to prevent/resist spring squish with larger profile cams?

You're correct. Uprated valve springs also are necessary for cams that have steeper closing ramps, the faster a valve closes the greater the potential for the valve to bounce off the seat.

[Icsunonove]

Ian, sounds really good

What maximum RPM are you looking at?

Have you considered upgrading the big end bearings to King or ACL or another manufacturer or are you going with Toyota?

[Jim-SR]

my build, when it happens, will consist of...

Custom grind cams (in the 305deg duration and around 10.5mm lift)
Carrillo forged H-Beam rods (old style with 40mm big end)
Wiseco, Mahle or Wossner forged pistons, depending on what i decide. already got a set of Wiseco ones which have been CNC finished for use in an Atlantic engine but fancy a set of Mahle's (theyre lighter)
Smallport head with extensive port reworking
Custom plenum inlet manifold (throttle bodies are alright for a quick and easy fix, but to do things properly youve got to keep it single throttle body and plenum!)
VEMS or Emerald standalone engine management
Aero profiled crank
Lightweight flywheel (3.5kg or thereabouts)
Fully balanced rotational and reciprocating assemblies (crank, pulleys, flywheel, clutch cover, pistons, rods, etc)
Early clutch setup (not sure which manufacturer yet though, will run standard friction plate and an uprated pressure plate though. i want early setup because its lighter with less rotational mass being smaller diameter. the power handling is more than enough)

should be running about 11:1 compression, 9000-9500rpm, 200bhp and a powerband from around 6500-9000rpm. im going to de-tune it though so that its got an over-safe working margin to ensure i get a decent rebuild interval out of it. anything over 5-10k would be satisfactory, over 20k would be an acheivement!!

first build im going to do though as a temporary fix is to run stock bottom end at stock revs, small port head and custom inlet manifold 272 or 288 degree cams, lightweight flywheel, either standalone engine management or a Greddy eManage as a short term fix, just mildly fettled for a solid 160bhp. should have that sorted by August hopefully, im too busy getting the chassis and suspension sorted at the moment to find the time to spend on the engine stuff. ive got most of the expensive parts already, just need to find time to use them lol

[jrleech]

Ian,

I like the look of the Haltech ECU, but one of the main critical bits in what ECU is having someone good who can tune it properly. Is there anyone in the UK with good experience with the Haltech?

Knock sensor seems like a sensible idea.

I'm sure I remember reading that the 4AGE head responds very well to high lift cams, but you really need to go to a shimless bucket design (was it the Yaris ones that are supposed to fit?).

Fuel pump? Anyone know what the stock pump is good for? I suppose SC injectors would be a good upgrade.

-------------------------

Jim,

Very nice . 305 cams, that'll sound racy!

When you get your custom plenum inlet manifold made up, are you just doing a 1 off, or can you do another one and sell it to me?

I was planning on a very similar spec, again de-tuned to about 180bhp so it lasts longer and is a bit more drivable at lower revs.

Can anyone recommend a decent book on inlet design? Fancy reading up on it.....

[Lauren]

Just a thought, with high rpms you may well want to switch to the yaris bucket shims as they are single piece so avoid the possibility of valvetrain bounce at higher revs.

I would be tempted to up the compression ratio and go for forged pistons if you can afford it.

Are you going to source some throttle bodies from a 20v or are you going aftermarket like Jon was saying?

[Speedy]

Just a thought, with high rpms you may well want to switch to the yaris bucket shims as they are single piece so avoid the possibility of valvetrain bounce at higher revs.

I would be tempted to up the compression ratio and go for forged pistons if you can afford it.

Are you going to source some throttle bodies from a 20v or are you going aftermarket like Jon was saying?

I have the yaris conversion on the Supernail Head - will look out some pictures.

[Lauren]

Jim, impressive build.

Can i ask why though you think a single plenum is advantageous over throttle bodies, given that pretty much any performance engine i can think of runs on throttle bodies as well as pretty much every race car that doesn't have restrictions in their series.

[mad man dan]

A plenum chamber with single throttle body will offer less restirction than four ITBs at certain rpms

I'm surprised you didn't know that.

[Speedy]

A plenum chamber with single throttle body will offer less restirction than four ITBs at certain rpms

I'm surprised you didn't know that.

Interesting - examples, linkage?

[Lauren]

A plenum chamber with single throttle body will offer less restirction than four ITBs at certain rpms

I'm surprised you didn't know that.

I was surprised that i didn't know that either. Would you be so kind as to explain further please?

[mad man dan]

No I won't because you are the tuning experts not me, remember?

MOD EDIT [off topic reply]

[Lauren]

No I won't because you are the tuning experts not me, remember?

MOD EDIT[off tpoic]:

Dan, I asked you a question because i don't understand the reasoning behind it. Yes i have a decent amount of knowledge but if i don't know something i will ask.

[anna]

Please keep this on topic for the sake of the original poster.

Regards,
Anna

[Speedy]

Ok - In answer to the question (and we might want to split this out into another thread perhaps), I've found this :

http://www.honda-tech.com/zeårothread?id=1776185&page=2

Think back to the days of ITBs on carbureted applications, side draft/ down draft webers etc. At partial throttle openings you get a higher inlet charge velocity (down-stream of the butterfly) which gives more mid range torque due to ram effect of the charge, whereas a single throttle body at the end of a plenum sees the entire column of charge in the runner moving very slow when at low and mid power demands.
However, if you look at old aggresive race cars with big power (individual runner style) you will see very large diamerter butterflys, this was not only for accomodating a large choke, but also to diminish the restriction which is caused by the butterfly and shaft at WOT, but then catch 22 comes into play and mid range torque drops off due to the large runner and butterfly dia. The trick equipment used slide plate throttle bodies which eliminated the butterfly and shaft, but kept the throat diameter a bit tighter sustaining a higher inlet charge velocity.
To this day I remain surprised that this concept of an accerlerated charge works because a partially open butterfly seems like an extreame turbulence causing restriction, but it does works.

[mr2mk1chick]

keep on topic - i've edited the rubbish

[Speedy]

I can also imagine that 4 ITBs would be a right PITA to balance and tune properly?

[Lauren]

Ok - In answer to the question (and we might want to split this out into another thread perhaps), I've found this :

http://www.honda-tech.com/zeårothread?id=1776185&page=2

Think back to the days of ITBs on carbureted applications, side draft/ down draft webers etc. At partial throttle openings you get a higher inlet charge velocity (down-stream of the butterfly) which gives more mid range torque due to ram effect of the charge, whereas a single throttle body at the end of a plenum sees the entire column of charge in the runner moving very slow when at low and mid power demands.
However, if you look at old aggresive race cars with big power (individual runner style) you will see very large diamerter butterflys, this was not only for accomodating a large choke, but also to diminish the restriction which is caused by the butterfly and shaft at WOT, but then catch 22 comes into play and mid range torque drops off due to the large runner and butterfly dia. The trick equipment used slide plate throttle bodies which eliminated the butterfly and shaft, but kept the throat diameter a bit tighter sustaining a higher inlet charge velocity.
To this day I remain surprised that this concept of an accerlerated charge works because a partially open butterfly seems like an extreame turbulence causing restriction, but it does works.

hmm yep, okay, but it still doesn't really explain why a single plenum will be better. Have i missed something here?

So i'm right in thinking that a single plenum would be better for mid-range torque?

Okay sounds fair enough. Must admit though when i do get round to building a revtastic NA i will be focusing on top end more and was thinking 20v which obviously comes with ITBs.

[Lauren]

I can also imagine that 4 ITBs would be a right PITA to balance and tune properly?

Hmm i've had twin 45 dellortos before.. they were a bit of a nightmare, though its easier i think (i could be wrong) with ITBs simply because you can tune more from the engine management side of things. Once they are balanced they really ought to remain so if the linkage is any good.