This is me fully in "hobby mode", this is an experiment and NOT a guide / how-to etc.
Basically I blew up my AW11's 4AGE and thought "I'll just clean up a spare head and do a simple 1.8ish coversion using the 7AFE block". As normal I got carried away, I thought "may as well go big valve to help the extra 200cc's worth of charge" etc and it went from there!
The old 4AGE head, I think I can see what was wrong!
The standard bigport 4AGE inlets:
Modifying the inlets:
Going big-valve, note the change in the gap between standard valves and new valves!
Nice new oversize wasted-stem valves:
Finished chambers, de-shrouded the valves, opened up ports, 4-angle seats (inlet):
Finished inlets, valve guide and boss removed! (maybe a bit extreme...!):
Old vs recon/modded!
Exhaust manifold de-dingleberried then flowed 1mm oversize radially to improve the anti-reversion/standing wave formation step (head flowed to match gasket, manifold is bigger:
Covers cleaned, painted in high-temp matt black then draw-filed by hand:
Not shown are inlet manifold and TVIS port-matched, exhaust valve gaps to be run way oversize to increase valve speed off seat (increasing wave/pulse formation and pressure at the expense of a tiny bit of lift and duration), cams to be re-timed by drilling/slotting the pulleys (over and above mods needed to get in line with the 7AFE bottom end), and other bits and bobs.
POWER ---------------------------------------------------
Well, using very basic crazymaffs:
128bhp plus cone filter and straight through exhaust = maybe 135bhp if I'm lucky?
Assuming 135bhp, 135 / 1.587 (1587cc) = 85.07bhp/L.
85.07 x 1.762 (1762cc) = 149.9bhp.
In terms of added poke, there could be a 5-15% gain in power from the ruthless flowing, call that 5% = 149.9 x 1.05 = 157.4bhp
Then the valve area has gone up by 10.1% and 16.5%, looking like this:
29.5mm dia Toyota small port in = 683mm area (94% of the bigport valve)
30.5mm dia Toyota Bigport in = 730mm area Bigport
25.5mm dia Toyota ex = 510mm area Bigport
32.0mm dia Atlantic in = 804mm area (110.1% of the bigport valve)
27.5mm dia Atlantic ex = 594mm area (116.5% of the bigport valve)
In actual fact the EFFECTIVE diamter of the new valves is even more, as I'm running much smaller seat contact areas, making it more like a 20% increase.
157.4bhp x 1.2 = 188.8bhp
In reality I'm expecting about 160bhp +/- 10% once set up properly, at 1,000 less RPM, with much more torque due to the longer stroke.
The theory from the point of view of air entering the port.
1 - Upper port (is this the part you refer to as the "runner"?). Standard, just had casting marks removed to maintain velocity and improve the boundary layer.
2 - Valve guide boss. These are there to support/cool the guide, and also in the GE head they appear to induce rotation in the flow over each valve as they are very lopsided (plus the ports are angled in pairs when looked at from above, not parallel!). The outside curve of the port is the highest velocity area as the air tries to keep going in a straight line, so I wanted to know what effect removing them would have (this probably means more revs or more lift needed).
3 - Valve guides, these were in the way of removing the guide bosses! Of course I know a cylinder is a pretty good aerodynamic shape so they are not a real problem if retained...
4 - The throat, this is the real venturi as it's right behind the valves and is the smallest area (especially now!). All I did to these was remove the "step" caused by mis-alignment between the port and ID of the steel valve seat insert. Doing this opened the seats up to about where I wanted to go due to the bigger valves anyway.
I'm keeping the standard cams, and I WAS going to stay at the same capacity to do a fair test of the effects - but decided not to bother and to try the 7A one straight away as I've not got heaps of spare time for multiple engine configurations/comparisons.
NOTE: Again this is me in "hobby mode", I don't pretend to know my way round engines to any real level!!!
4AGE gas flowing and big valves etc
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4AGE gas flowing and big valves etc
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Re: 4AGE gas flowing and big valves etc
For someone in "hobby mode" that is some damn fine work there Keri
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Re: 4AGE gas flowing and big valves etc
PW@Woodsport wrote:For someone in "hobby mode" that is some damn fine work there Keri
Cheers old bean!
One of these days I may even put it in the car and see if it goes bang!
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Re: 4AGE gas flowing and big valves etc
nice work
i'd love to have a go at something like that myself sometime
i'd love to have a go at something like that myself sometime
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Re: 4AGE gas flowing and big valves etc
I was going to ask if that is yours on eBay at the moment with the Toda 304 deg 8.5mm lift cams, but its not.
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Re: 4AGE gas flowing and big valves etc
SuperRedMR2 wrote:I was going to ask if that is yours on eBay at the moment with the Toda 304 deg 8.5mm lift cams, but its not.
Nope, not mine. I'd like to get the best bits of both though!
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Re: 4AGE gas flowing and big valves etc
I was considering this, as its a darn site cheaper than buying the camshafts outright in the first place.
With those cams though, would it idle like a lumpy b1tch? What hp would I gain?
With those cams though, would it idle like a lumpy b1tch? What hp would I gain?
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Re: 4AGE gas flowing and big valves etc
SuperRedMR2 wrote:I was considering this, as its a darn site cheaper than buying the camshafts outright in the first place.
With those cams though, would it idle like a lumpy b1tch? What hp would I gain?
They are probably too high duration for the standard MAP sensor driven ECU to cope, so you would need to run and aftermarket one and/or sidedafts / throttle bodies, but beyond that I can't really comment!
Have a read of this site as the guy has messed about with the 4AGE a lot more than me!
www.billzilla.org/4agstock.htm
and
www.billzilla.org/4agmods.htm
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Re: 4AGE gas flowing and big valves etc
Hi Keri, how did you go about getting the valve guides out?
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Re: 4AGE gas flowing and big valves etc
Bender Unit wrote:Hi Keri, how did you go about getting the valve guides out?
I didn't! I should have replaced them as the first job, but this was one that kind of got out of hand.
I might replace them but it will mean re-doing the seats so I'll probably save that for phase 2....if there is ever a phase 2, I quite fancy a 2.0 BEAMS next.
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Re: 4AGE gas flowing and big valves etc
So you just ground the guides down as you did the port?
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Re: 4AGE gas flowing and big valves etc
Bender Unit wrote:So you just ground the guides down as you did the port?
Yup!
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Re: 4AGE gas flowing and big valves etc
Interesting - get it on a car I want to see it work!
(I've got TRD OS Valves in my engine, always wondered about gains so that's interesting info ).
(I've got TRD OS Valves in my engine, always wondered about gains so that's interesting info ).
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Re: 4AGE gas flowing and big valves etc
tonigmr2 wrote:Interesting - get it on a car I want to see it work!
(I've got TRD OS Valves in my engine, always wondered about gains so that's interesting info ).
Were the ports / throats modified or just the valve seats?
I agree, some rolling road comparisons would be interesting, but there are soooo many variables we won't be able to draw any sensible conclusions.
I know someone with a flow bench etc and I was going to replicate the mods on some of the ports on the old head and compare with the standard ports etc.
The trouble is I hate doing anything like this by hand, I would like to do a CAD model and get the ports CNC machined...but that wouldn't line of with the casting perfectly, which was Toyota's problem in the first place and why the steps are there.
Last edited by Keri-WMS on Tue Jan 12, 2010 5:29 pm, edited 1 time in total.
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Re: 4AGE gas flowing and big valves etc
...duplicated post! (I can't see how to delete it?)
Last edited by Keri-WMS on Tue Jan 12, 2010 5:31 pm, edited 1 time in total.
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Re: 4AGE gas flowing and big valves etc
Everything is modified - and I'm using a small port head...!
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Re: 4AGE gas flowing and big valves etc
tonigmr2 wrote:Everything is modified - and I'm using a small port head...!
Cool! Very different from mine then - any photos or details out of interest?
I remember reading here about a small port formula atlantic head with loads of mods including blanked injectors, was that you?
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Re: 4AGE gas flowing and big valves etc
This is not my thread it's yours. I think there are some pictures of the modified head etc. on my engine in the project cars section - and a link to the car is in my sig.
Seriously, you need to try out your hobbying on a working car. It'd be very interesting!
Seriously, you need to try out your hobbying on a working car. It'd be very interesting!
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Re: 4AGE gas flowing and big valves etc
True, 'tis my thread.....and I agree, I miss the MR2 badly - it's been off the road for ages.
Here's that thread by the way, looks like it's a bigport anyway, my mistake: www.imoc.co.uk/forums/viewtopic.php?t=109352
Here's that thread by the way, looks like it's a bigport anyway, my mistake: www.imoc.co.uk/forums/viewtopic.php?t=109352
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Re: 4AGE gas flowing and big valves etc
Ah yes Chris, the other manic 4ag tuner.
Has your car been off the road as long as mine...2006 and counting!!
Has your car been off the road as long as mine...2006 and counting!!