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Old 03-24-2012, 11:44 PM   #1
lieutenantcolumbo
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Default Valves - Oversize Intake / Standard Exhaust?

Having a block built. It's strictly for a daily driver, no tracking or racing.

Looking to improve on the power I already have while and also maintaining or improving the left of the curve. The emphasis is more on 0-80 mph than top end or 1/4 mile times.

One idea thrown out was maybe going just +1mm on the intake valves and keep the exhaust standard size. Don't think I've seen this done before, so just wondering if anybody has any experience with this?

Here's the highlights of the build (* indicates new parts).

Block:
Manley Platinum Series Pistons *
Manley H Beam Connecting Rods *
Nitrided Crank * 11mm Oil Pump *
ACL Main & Rod Bearings *
KillerB Pickup/Windage Tray/Pan *

Heads/Plugs:
Kelford R-199-A *
Manley Extreme Duty Exhuast Valves 32mm *
Manley Race Flow Intake Valves 37mm *
Manley Valve Spring and Retainer Kit *
Valve Job *
NGK Iridium One Step Colder Spark Plugs *

Turbo/Exhaust:
AVO380 Turbo
Cobb Down Pipe
Up Pipe / 38mm External Waste Gate *
Route EWG Dump Tube to DP *
Agency Power ELH *
SPT Cat Back
GrimmSpeed EBCS *

Intake:
Custom Big MAF *
AVO Cold Airbox
AVO Silicone Inlet
PW Intercooler *

Fuel:
DW850's
AVO 245lph Fuel Pump

Meth:
Labonte Water/Meth Kit
AEM 30-3020 Fail Safe & Snow SafeInjection *
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Last edited by lieutenantcolumbo; 03-25-2012 at 09:04 AM.
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Old 03-25-2012, 08:52 PM   #2
lieutenantcolumbo
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t....t....t
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Old 03-25-2012, 10:10 PM   #3
04ImprezaWRX
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If its your daily keep it simple, no?
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Old 03-26-2012, 12:41 AM   #4
B.R.E.D
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A couple of questions first.

Who is building your engine?

Do you plan to stay with the AVO380?

If not what are your power goals for the future?
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Old 03-26-2012, 12:53 AM   #5
lieutenantcolumbo
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Quote:
Originally Posted by B.R.E.D View Post
A couple of questions first.

Who is building your engine?

Do you plan to stay with the AVO380?

If not what are your power goals for the future?
IAG will do the build.

Yes, I plan to stay with the AVO380 for a while, probably for a couple years at least. I have had it since Dec 2009 and overall am pretty happy with it. With the mods I am making I hope to squeeze a little more out of it.

My car has a built 5EAT that has been performing perfectly since Feb 2010 (yes it only took 2 months for the AVO380 to turn it into a 3EAT) but I really don't want to find out its limits. With a mild launch from just about 2200rpm I was able to get 4.637 0-60 time. Several on LTG.com have been able to get 3.8 0-60's with the same turbo, but they had M/T's, launched more aggressively, and were using meth. I be pretty happy if I could close the gap a just little more, not looking for anything too crazy.

Thanks in advance!

Last edited by lieutenantcolumbo; 03-26-2012 at 01:02 AM.
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Old 03-26-2012, 01:15 AM   #6
lieutenantcolumbo
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Quote:
Originally Posted by 04ImprezaWRX View Post
If its your daily keep it simple, no?
That is a legitimate point.

Probably from a resale point if parted out I guess it would be better to either have both valves standard or +1mm, since there doesn't seem to be a lot of info out there on this suggestion.

Either way I like to find out the answer though.
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Old 03-26-2012, 02:11 AM   #7
B.R.E.D
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Quote:
Originally Posted by lieutenantcolumbo View Post
IAG will do the build.

Yes, I plan to stay with the AVO380 for a while, probably for a couple years at least. I have had it since Dec 2009 and overall am pretty happy with it. With the mods I am making I hope to squeeze a little more out of it.

My car has a built 5EAT that has been performing perfectly since Feb 2010 (yes it only took 2 months for the AVO380 to turn it into a 3EAT) but I really don't want to find out its limits. With a mild launch from just about 2200rpm I was able to get 4.637 0-60 time. Several on LTG.com have been able to get 3.8 0-60's with the same turbo, but they had M/T's, launched more aggressively, and were using meth. I be pretty happy if I could close the gap a just little more, not looking for anything too crazy.

Thanks in advance!
I would ask IAG their thoughts on it.

At our shop almost all of our heads leave with 1mm oversize valves in them. We also open up the seats and match the port to the seat paying very close attention to the bowl area behind the valve. Most shops don't do this and without it oversize valves are a waste of money.

With a turbo that small I think I would probably stay with stock size valves all around as I think that it would be better to error on the side of higher port velocity.

As an engine builder I ask a lot of questions of my customers when we start a project, you have to look at the engine as a total package.


IAG seems to be good guys I don't know a lot about the engine program they have going there or if they have one at all so I'm not sure what they offer. I think the best thing to do is call and talk with one of the guys there first.
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Old 03-26-2012, 09:04 AM   #8
Turn in Concepts
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we have done it. the reasoning is based upon info that we've seen on valve area comparison and size of intake vs exhaust. according to the information we saw moving the intake to +1 makes the ratio between intake and exhaust in a better "sweet spot."

as for whether or not it works - yeah. motor still ran just fine. as for whether or not it helped. I honestly don't know. There's so much that changed on the motor for that build that we really can't be sure.
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Old 03-26-2012, 09:30 AM   #9
speedy mike
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Usually increasing the size of the intake valves moves
the sweet spot to a higher rpm. 1 mm ? Can't see the value
for street use and occasional drag race. You can drive your
self crazy and poor.

Live Long and Prosper
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Old 03-26-2012, 08:38 PM   #10
lieutenantcolumbo
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Thanks for all the responses.

The builder threw out that idea mainly based on my goal to maintain or improve the left side of the curve and improve spool. I knew increasing both valves +1mm would probably move the curve to the right, but I hadn't seen anybody ever mention just doing one or the other.
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Old 08-13-2016, 02:36 PM   #11
DrthVadr
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Default resurrection

264/260 cam

Last edited by DrthVadr; 08-14-2016 at 11:18 PM.
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