427 intake manifold options
11-28-2017, 06:53 PM
#1
Staging Lane
Thread Starter
Join Date: Jan 2010
Posts: 57
Likes: 0
Received 0 Likes
on
0 Posts
427 intake manifold options In the process of building a 427 for a 2002 Camaro. LS3 heads. Looking for manifold options that don't require cutting into the cowl. I checked out the Fast with the race runners Texas Speed is offering and I'm looking at the Holley Low profile Sheet metal manifold. I will be using nitrous and looking for a power band of 6000 to 7000rpm. Does anyone one have any experience with either of these manifolds in a similar combo?
11-28-2017, 10:48 PM
#2
TECH Fanatic
Join Date: Aug 2009
Location: Coast of San Mateo County Between Pacifica & HMB
Posts: 1,815
Received 215 Likes
on
128 Posts
LS3 Heads with 427" with a 6000-7000 RPM Band might perform better
With the Mid Length Runners VS the shorter Race Runners.
Which Heads & Cam Specs?
With the Mid Length Runners VS the shorter Race Runners.
Which Heads & Cam Specs?
11-29-2017, 07:56 PM
#3
Staging Lane
Thread Starter
Join Date: Jan 2010
Posts: 57
Likes: 0
Received 0 Likes
on
0 Posts
I would spin it higher than 7000 if I could get enough intake manifold on it.
11-29-2017, 09:49 PM
#6
TECH Fanatic
Join Date: Aug 2009
Location: Coast of San Mateo County Between Pacifica & HMB
Posts: 1,815
Received 215 Likes
on
128 Posts
The Race Runner crossover RPM for a 4" Stroke would be roughly
7500 RPM.
Hammer & I both utilized Mid Length Runners with LS3 Style Heads
That peak about 7200 & Carry to 7800 with 3.60" & 3.622" Strokes.
4.0" Stroke has ~ 10% greater piston speed at the same RPM.
7500 RPM with your 4" Stroke = 8250 in ours.
So at the track shifting over 7500 the Short Race Runners would
Be the way to go and Mids if you drive on the street.
The runners are relatively inexpensive and easy enough to swap
Out and test for yourself.
7500 RPM.
Hammer & I both utilized Mid Length Runners with LS3 Style Heads
That peak about 7200 & Carry to 7800 with 3.60" & 3.622" Strokes.
4.0" Stroke has ~ 10% greater piston speed at the same RPM.
7500 RPM with your 4" Stroke = 8250 in ours.
So at the track shifting over 7500 the Short Race Runners would
Be the way to go and Mids if you drive on the street.
The runners are relatively inexpensive and easy enough to swap
Out and test for yourself.
11-29-2017, 11:16 PM
#7
10 Second Club
Fast intake with Mid runners, minimum. I take my 388 ls3 as high as 8000 with that setup. As far as runners go they'll flow more than your heads will.
Now I went to a 105 Holley TB and ported the intake inlet to 107 as I was getting a touch of plenum vacuum at high rpm. This does eliminate the oring gasket though, but the 105 comes with a paper gasket and I fogged it good with high tack.
If you're working around the cowl on an fbody then the fast is the easiest and most versatile IMO
if you ever want to try the shorter runners, you can! That's the beauty
Now I went to a 105 Holley TB and ported the intake inlet to 107 as I was getting a touch of plenum vacuum at high rpm. This does eliminate the oring gasket though, but the 105 comes with a paper gasket and I fogged it good with high tack.
If you're working around the cowl on an fbody then the fast is the easiest and most versatile IMO
if you ever want to try the shorter runners, you can! That's the beauty
Trending Topics
11-30-2017, 06:46 AM
#8
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,446
Received 1,835 Likes
on
1,145 Posts
Beauty, eh?
12-01-2017, 03:59 PM
#9
Staging Lane
Thread Starter
Join Date: Jan 2010
Posts: 57
Likes: 0
Received 0 Likes
on
0 Posts
I decided to give Fast a call today. Since I use nitrous and my converter will flash to about 6000 rpm, and the rpm will not fall below 6000 rpm on the shifts, they suggested the short race runners. He also gave me a part number for the manifold with those runners already installed.
I mistakenly thought the manifold texas speed has on the site was with the race runners when it actually has the mid length runners.
The race runners in the Fast don't look much different in length to the runners on the low profile Holley manifold. Holleys runners are straight which I prefer. Cost really isn't the issue here even though the Holley is a good bit less expensive. I just wish knew someone who has used the Holley in a big inch n/a with nitrous application.
I mistakenly thought the manifold texas speed has on the site was with the race runners when it actually has the mid length runners.
The race runners in the Fast don't look much different in length to the runners on the low profile Holley manifold. Holleys runners are straight which I prefer. Cost really isn't the issue here even though the Holley is a good bit less expensive. I just wish knew someone who has used the Holley in a big inch n/a with nitrous application.
12-14-2017, 08:31 PM
#10
Staging Lane
Thread Starter
Join Date: Jan 2010
Posts: 57
Likes: 0
Received 0 Likes
on
0 Posts
I ended up going with the fast with the race runners. I can tell by looking at it that a plate nitrous system isn't going to be ideal with these runners. I'm gonna cut the throat out a bit and add a 105mm throttle body from Holley. If its a turd I'll swap to the mid length runners and give that a try but I feel that with this many cubes, the short runners will be my best choice.
12-15-2017, 09:47 AM
#12
Staging Lane
Thread Starter
Join Date: Jan 2010
Posts: 57
Likes: 0
Received 0 Likes
on
0 Posts
Maybe. My converter will give me a 6000rpm flash when I'm done. So with that being the lowest rpm it will see, hopefully the short runners will provide more average power from 6000 rpm up.
