Expected gains from a GT40 intake on an otherwise stock motor

ReverendDexter · February 21st, 2010, 08:10 PM

Just curious what, if any, gains can be had from a GT40 intake on an otherwise stock '90 5.0.

Also wondering at what power level does that intake start becoming a restriction.

93hatch · February 21st, 2010, 09:13 PM

Prob 10ish, I ran it on stock heads for awhile, just seemed to broaden the curve a bit, didnt die as soon

JBIGBOOTSY · February 22nd, 2010, 06:15 AM

Originally Posted by ReverendDexter

Just curious what, if any, gains can be had from a GT40 intake on an otherwise stock '90 5.0.

Also wondering at what power level does that intake start becoming a restriction.

THe best stock intake runner flows about 200cfm, the worst, 150's

the heads flow about 190-200.

ReverendDexter · February 22nd, 2010, 10:24 AM

Originally Posted by JBIGBOOTSY

THe best stock intake runner flows about 200cfm, the worst, 150's

the heads flow about 190-200.

Okay, cool. So, by my math, at 100% VE, that 150cfm runners are gonna limit the car to just shy of 4300 rpm, the 200s to just shy of 5700.

And, now for a total newb question, what's a reasonable VE to expect?

And are those limited runners at least part of the reason why you don't get 100% VE? Because they just can't flow enough to refill the cylinder?

MustangMatt96GT · February 22nd, 2010, 01:17 PM

VE i would expect would be near 75-80 percent honestly... Not anything scientificly calculated there, but it could be a little higher near 85 percent... Even on the full out race motors we are lucky to see over 93 % or so... Can NEVER have 100% VE

ReverendDexter · February 22nd, 2010, 01:41 PM

Okay, assuming a 5.0L engine, my math is right and lower VE allows a poorer-flowing passage to support more rpm (as there's effectively less cylinder to fill), at 80% VE, a 150cfm runner should support just shy of 5400 rpm, 93% would knock that down to just over 4600 rpm.

That *seems* to make sense, and if it is right, I see why the GT40 intake isn't that popular around here.

8URSRT · February 22nd, 2010, 01:46 PM

You won't see a real big gain from the intake by its self on a stocker. It will a step in the right direction when you start adding other parts.

Power wise these intakes perform rather well when ported. The current combo on my Coupe includes a ported GT-40 and it made 488 HP and 463 TRQ. Power was falling off about 6400, which wasn't too huge of a deal because that is where I shift at anyways.

This is all being done with a 150,000 stock short-block also.

Rusty105 · February 22nd, 2010, 02:34 PM

Originally Posted by MustangMatt96GT

VE i would expect would be near 75-80 percent honestly... Not anything scientificly calculated there, but it could be a little higher near 85 percent... Even on the full out race motors we are lucky to see over 93 % or so... Can NEVER have 100% VE

I do not agree with this. While rare, it can be obtained N/A

Forced is easy.

ReverendDexter · February 22nd, 2010, 02:41 PM

Originally Posted by Rusty105

I do not agree with this. While rare, it can be obtained N/A

Isn't that due to intakes that can create a supercharging effect at certain rpms?

JBIGBOOTSY · February 22nd, 2010, 03:36 PM

I have 100% VDs!!!

Iwannagofast · February 22nd, 2010, 03:40 PM

Originally Posted by JBIGBOOTSY

I have 100% VDs!!!

uh oh, are u wearing protection because i hate catching viruses online

ReverendDexter · February 22nd, 2010, 03:53 PM

Originally Posted by Iwannagofast

uh oh, are u wearing protection because i hate catching viruses online

that's what Trojans are for....

err, maybe not.

ryans88gt · February 22nd, 2010, 04:16 PM

Originally Posted by MustangMatt96GT

VE i would expect would be near 75-80 percent honestly... Not anything scientificly calculated there, but it could be a little higher near 85 percent... Even on the full out race motors we are lucky to see over 93 % or so... Can NEVER have 100% VE

Actually many very high performance motors (talking extremes here) have over 100% VE at high RPMS due to scavenging and ramming effects of high velocity air.

MustangMatt96GT · February 22nd, 2010, 06:01 PM

Originally Posted by ryans88gt

Actually many very high performance motors (talking extremes here) have over 100% VE at high RPMS due to scavenging and ramming effects of high velocity air.

yes i will agree... im just saying from my experience that is a HUGE $$$$ motor.... but it is hard to get a 100% VE motor NA cheap, and pretty easy to do when you are compressing air before hand.

tmoss · February 22nd, 2010, 10:18 PM

stock E7s flow ~160cfm tops and GT40s flow ~190cfm tops

A stock HO intake flows ~150cfm average. A properly ported HO intake will flow 200cfm through a smaller cross section than the GT40/Cobra/Explorer that flows ~205-210cfm stock. Port the lower of the GT40s and the intake will flow 240-250cfm.

Good N/A race engines can hit about 120% VE or maybe a little more if your a real good engine builder.

Timm10221 · February 22nd, 2010, 10:25 PM

Not to be the newbist of newbs but whats VE... I am thinking it has to do with velocity forcing air into the engine / compressing it.. am I on the right track.. I need to be be schooled here haha

FastStang91Lx · February 22nd, 2010, 10:27 PM

Volumetric Efficiency

tmoss · February 22nd, 2010, 10:34 PM

if a piston/bore displaces 50ci, and it pulls in 50ci then it is 100% volumeteric efficiency. Race engines and others can get more into the cylinder when the exhaust has done a good job of scavanging the chamber of all spent gasses and the inlet air speed is high enough that the mass (weight) of the air column in the runner forces air into the chamber as the valve closes ABDC.

Timm10221 · February 23rd, 2010, 08:11 AM

FastStang and tmoss, Thank you. Make good sense to me!

fastback lover · February 23rd, 2010, 10:21 AM

Thank you guys. I even learnt something new. haha.

February 21st, 2010, 08:10 PM	#1
ReverendDexter Priest of the Car Gods Clapped-out '90 GT 'vert ~5.5 seconds off TTOD :( Join Date: Jan 2007 Location: Rohnert Park, CA Posts: 13,233 iTrader: 0 reviews	Expected gains from a GT40 intake on an otherwise stock motor Just curious what, if any, gains can be had from a GT40 intake on an otherwise stock '90 5.0. Also wondering at what power level does that intake start becoming a restriction. __________________ O o /¯/______________________ \|BLAAAAAAAAAAAAAAAAAAAAAAAAARGH!!! \_\ Buy my Bronco, special deal for MM folks

February 21st, 2010, 09:13 PM	#2
93hatch Banned 1992 Lx 11.39@119.24 Join Date: Jan 2008 Location: Az Posts: 11,665 iTrader: 0 reviews	Prob 10ish, I ran it on stock heads for awhile, just seemed to broaden the curve a bit, didnt die as soon __________________ [QUOTE=93mustank;2577445]We speed tested my right arm for quickness in shifts... So he could design the cam for proper shift recovery.[/QUOTE]

February 22nd, 2010, 01:17 PM	#5
MustangMatt96GT Proud American 1996 Mustang GT 10.76 @ 122 with d/a of 8365 ft Join Date: Dec 2006 Location: Lakewood, CO Posts: 10,171 iTrader: 3 reviews	VE i would expect would be near 75-80 percent honestly... Not anything scientificly calculated there, but it could be a little higher near 85 percent... Even on the full out race motors we are lucky to see over 93 % or so... Can NEVER have 100% VE __________________ RIP Travis Billings Special Thanks to: Andrews Racing Transmissions Baseline Suspensions Blown Small Block Ford with a hole in the block. 9.5 Dart Block 400 CI being saved for. Just because you can fuck a cactus doesn't mean you should. Never Lift Racecars

February 22nd, 2010, 01:41 PM	#6
ReverendDexter Priest of the Car Gods Clapped-out '90 GT 'vert ~5.5 seconds off TTOD :( Join Date: Jan 2007 Location: Rohnert Park, CA Posts: 13,233 iTrader: 0 reviews	Okay, assuming a 5.0L engine, my math is right and lower VE allows a poorer-flowing passage to support more rpm (as there's effectively less cylinder to fill), at 80% VE, a 150cfm runner should support just shy of 5400 rpm, 93% would knock that down to just over 4600 rpm. That seems to make sense, and if it is right, I see why the GT40 intake isn't that popular around here. __________________ O o /¯/______________________ \|BLAAAAAAAAAAAAAAAAAAAAAAAAARGH!!! \_\ Buy my Bronco, special deal for MM folks

February 22nd, 2010, 01:46 PM	#7
8URSRT Newbie 1989 Coupe 11.49@124 Join Date: Jan 2010 Location: MO Posts: 47 iTrader: 0 reviews	You won't see a real big gain from the intake by its self on a stocker. It will a step in the right direction when you start adding other parts. Power wise these intakes perform rather well when ported. The current combo on my Coupe includes a ported GT-40 and it made 488 HP and 463 TRQ. Power was falling off about 6400, which wasn't too huge of a deal because that is where I shift at anyways. This is all being done with a 150,000 stock short-block also. __________________

February 22nd, 2010, 03:36 PM	#10
JBIGBOOTSY MM Fanatic 1990 LX hatch Join Date: Aug 2006 Location: Hobart Indiana Posts: 4,392 iTrader: 0 reviews	I have 100% VDs!!! __________________ Bolt-on Abraham Lincoln Log motor. With extra wiring.

February 22nd, 2010, 10:18 PM	#15
tmoss Regular Join Date: Jan 2007 Location: St Louis, Mo Posts: 382 iTrader: 0 reviews	stock E7s flow ~160cfm tops and GT40s flow ~190cfm tops A stock HO intake flows ~150cfm average. A properly ported HO intake will flow 200cfm through a smaller cross section than the GT40/Cobra/Explorer that flows ~205-210cfm stock. Port the lower of the GT40s and the intake will flow 240-250cfm. Good N/A race engines can hit about 120% VE or maybe a little more if your a real good engine builder. __________________ 88 GT Vert 5spd, 3:73 gears, Explorer intake/65mm TB, Explorer Ps, Manley race 1.85/1.55 valves, 1.7/1.6 stud rockers, stock cam +4 degrees, MAC Jet-Hot coated shorties. 277RWHP/330RWTQ www.fastlanecars.com http://tmossporting.0catch.com/

February 22nd, 2010, 10:27 PM	#17
FastStang91Lx MM Fanatic 1991 Mustang LX 5.0 Join Date: Jan 2010 Location: Minnesota Posts: 4,810 iTrader: 2 reviews	Volumetric Efficiency __________________ A whole bunch of crap that makes the car go fast

February 22nd, 2010, 10:34 PM	#18
tmoss Regular Join Date: Jan 2007 Location: St Louis, Mo Posts: 382 iTrader: 0 reviews	if a piston/bore displaces 50ci, and it pulls in 50ci then it is 100% volumeteric efficiency. Race engines and others can get more into the cylinder when the exhaust has done a good job of scavanging the chamber of all spent gasses and the inlet air speed is high enough that the mass (weight) of the air column in the runner forces air into the chamber as the valve closes ABDC. __________________ 88 GT Vert 5spd, 3:73 gears, Explorer intake/65mm TB, Explorer Ps, Manley race 1.85/1.55 valves, 1.7/1.6 stud rockers, stock cam +4 degrees, MAC Jet-Hot coated shorties. 277RWHP/330RWTQ www.fastlanecars.com http://tmossporting.0catch.com/

February 23rd, 2010, 10:21 AM	#20
fastback lover Zip Your my Hero.... 1988 Mustang LX N/A Join Date: Sep 2007 Location: Arizona Posts: 918 iTrader: 0 reviews	Thank you guys. I even learnt something new. haha.

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