To my understanding the lumpy idle is not a condition caused by a mismatch in duration, but a high duration, mismatched to some extent or not. Look for some 280 plus duration, but dont go too high as a 7a wont spin as fast as a 4a at the limiter.
Hi
I have a 4age head 20v and a 7afe block, im looking to make put some lumpy cams in the motor but im unsure what cams will be the right ones, can anyone explain how i would go about doing this? is it as simple as getting different cam duration's for the intake and exhaust?
Thanks
To my understanding the lumpy idle is not a condition caused by a mismatch in duration, but a high duration, mismatched to some extent or not. Look for some 280 plus duration, but dont go too high as a 7a wont spin as fast as a 4a at the limiter.
lobe separation angle is more the thing here. you probably want to do some reading, plenty of tech articles out there
And also talk to a cam place like https://www.kelfordcams.com/
Which if you're in NZ are same time zone.
Oh really...
Do some reading from camtech site. They have standard recommendations for mild, street and race.
https://camtechcams.com.au/
from site
Description:
272 Degree 8.6mm Lift. Slight lope at idle, good mid range power, suitable for std or slightly modified engines. RPM RANGE 3000-7000
Description:
280 Degree 8mm Lift. Rough idle, strong mid range and top end power, suitable for engines with limited modifications and increased compression ratio. RPM RANGE 3500-7500
Description:
280 Degree 8mm Lift. Rough idle, strong mid range and top end power, suitable for engines with limited modifications and increased compression ratio. RPM RANGE 3500-7500
Description:
290 Degree 8.6mm Lift. Rough idle strong mid range and top end. Suitable for modified engines with increased comp ratio. RPM RANGE 4000-8000
my previous RA28, R.I.P is here.
http://forums.toymods.org.au/index.p...t=0#msg_651396
Current build here.http://www.toymods.net/forums/showthread.php?t=33512
Hi, plans have changed, iv decided to turbo the 7age, probs run between 200-300 hp with a rev limit of about 7000 maybe 7500 on good days, im not to fussy about low end power as Gas prices have gone up, Im after instant power but doesn't need to be to aggressive til turbo/ vvt kicks in but still have a bit of go from a 20kph roll start race.
For turbo, you don't need bigger cams.
For example toyota kept the same sized cams in the supercharged variants of the 4AGE engines. All you need is flow and the 20v head flows very well from factory - it's proven.
Especially if it's a street vehicle you say you are 'after instant power' which is really 'torque'
The 7A block & vvt will give you torque. More important than cams is turbo selection.
A TDO4l will suit, they're plentifull and affordable.
OR..
If you willing to spend a bit more $ for earlier spool and broader power band, go for the disco potatoe Garret's GT28RS ball bearing turbo - there's 2 versions. One of them has a larger exhaust housing, so the power band is higher in the rev-range and a higher peak power figure is attained. My 2cents worth = the smaller version suits a street driven vehicle, ..but it's entirely up to you.
With the vvt working properly (they wear out and develop a ticking sound like a diesel engine), you'll have an excellent street engine with a good balance between torque and peak power.
NOTE: When researching 7AGE there's talk about weak factory conrods, machining oil-squirters in the block and adding hardened steel dowels into the crank where the flywheel bolts up. All those mod's a for high powered race-cars - you don't need them, even if you're doing a few track days.
There's very little evidence of broken factory rods, ..but still the rumour persists. The weak point is actually the bolts, but they can only be called weak in light of fully dedicated race builds at sustained 8000rpms with poor oil conditions and excessive frictional heat at the crank and connecting rod. (which is why race builds run forged rods and dry sumps)
The street build I've outlined will be good for occasional track days. The 20v head flows really well from factory which is critical to boosted applications.
If you want to maximise the camshaft operation (which is where power & torque can be adjusted and improved) ..just get adjustable cam-pulleys.
4AFE/gearbox issues, 4AGT/ZE replacement changes to fully blown 7AGTE project...
https://www.facebook.com/gerard.mang...1485304&type=3
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