ls1 intake vs truck intake. thoughts
03-01-2006, 10:03 PM
#12
TECH Fanatic
iTrader: (3)
Join Date: Oct 2003
Location: Winston Salem NC
Posts: 1,612
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by moregrip
Richard from WCCH did some flow testing on a stock truck manifold, he can shed some light on this discussion
I assume 1 runner is tested at a time?
I may be all wrong on this but,
I take it as the intake is pressurized, fills all voids and the air flows to the point of least resistance...one runner
great numbers as reference for the FI crowd but...
How much does this tell us NA guys
where camshaft selection and taking full advantage of the incoming air means so much...
same with heads
its only as good as whats behind it, right?
Even with heads attached I dont see how this can be representative
of whats exactly goin on , inside the engine
where the valves are opening and closing at different times all
8 of them
Looking at the truck intake I see a big fight over which runner is going to get the air
Loss of lowend TQ
I can barely accept that in a bolt on 5.3 but some of these guys are running big CI or
heads ,big cams, and so on
and if the intake is truly a restriction then the more the mods, CI, etc
the lower in rpm it shows its ugly head because its trying to pull more air
So with the ideal setup, would it be safe to say you may gain low end?
I dont see much issue with runner length
How would plenum volume play into this equation?
03-01-2006, 10:47 PM
#13
TECH Addict
OK....here's my $.02
My LS1 intake swap was apparantly much less complicated than what Kano went through to put an LS6 onto his truck, whether it was the combination of parts/years or just ****-luck I'm not sure
This is my story:
First and foremost: The reason I attemped this was was purely for asthetics....I wanted a manifold that was good looking, I never expected or even cared about a power difference. I will state that I did take a low-end torque hit from the manifold, this WAS before my heads/cam swap though so if I ever decide to do the swap back to the LS1 I'll bet I don't see a power loss
Parts I had to buy:
Speartech Idler Pulley Relocation Bracket: $75
90º Whipple Billet Aluminum radiator hose elbow $26
Thats it !!!
How I went about swapping:
The first problem I ran into was that the truck injectors are shorter than the f-body injectors so I had to figure out a way to mount the fuel rails....to do this I cut down the injector rail mounting posts .5" with a Dremel, I re-drilled the inside of the posts to accept the threaded brass inserts that were in the top part of the posts that I cut off (I cut them out of the plastic with the dremel) and then drove the insets back into the posts with a ball-peen hammer, The .5" I cut off wasn't exactly the length difference between the two injectors so I used small brass washers as shims to space the rails back up perfectly. I didn't run into the problem Kano had with the truck injectors not fitting into the manifold, mine dropped right in.
Second was the fuel crossover....I just stuck with the truck crossover, it was stupid looking but functional, I eventually planned on having a custom one bent up but ended up removing the manifold before I got around to it.
We've all figured out by now that the truck waterpump and the LSx manifold don't work together because of the outlet location of the waterpump, my solution was to buy the 90º outlet that Whipple sells for their supercharger kits, I cut down the outlet of the waterpump down to about .75" tall and flared the end with a pair of pliers (not pretty but effective for keeping the hose on), I butted the cut-down outlet and the 90º elbow together and used a piece of radiator hose and two clamps to hold them together (this is still on the truck as it was non-reversible). This cleared the cable driven TB I have by only about .020" but it DID clear and didn't rub at all so I was happy with the end result.
The fan.....I thought this was going to be a problem because I still have the mechanical fan on the truck (I live in the hottest place in the western hemisphere, I NEED to know my fan will ALWAYS work), as it turned out the factory intake tubing cleared the fan....certainly not by much (*maybe* .030") but again it DID clear and didn't touch under hard acceleration so I was happy.
Kano ran into problems with the PCV line from the pass. side valve-cover not having any place to plug into on the LS6 manifold, the '98 LS1 I have has a brass tube coming off the side of the intake in the same place as the truck manifold....I used that
The EGR WAS a pain in the *** to do....the trucks EGR pipe WILL work but you have to be extremely careful in bending it to meet up with the top-mounted opening in the LS1 manifold, it DOES work, I PROMISE, you just have to be PATIENT while bending the pipe.....it took me almost an hour of VERY SLOW bending to get it to line up
I re-used the factory gaskets....in fact I've had the manifold off 4 times and I'm still on the factory gaskets (and NO leaks !!)
I never bothered to hide the harness.....It was one of these "I'll get around to it eventually" things and eventually never came.
The relocation bracket was a no-brainer......I bolted it in and bought a new longer belt (sorry...I don't remember the length but it and the relocation bracket are still on the truck so I can get the part number at some point if I remember to)
As for making it all work together.....I installed all of it and it started the truck...it worked the first time
I ended up removing the manifold after about 6 months because I was having all kinds of tuning nightmares due to a crack on the side of the manifold where the top and bottom half were mated together....I'm pretty certain I caused this crack when the shelf that I had the manifold sitting on in my garage collapsed and the manifold bounced across the floor. At the time it was easier for me to just stick the truck manifold back on then to find another LS1 manifold.
There's my story...I'm sticking to it
My LS1 intake swap was apparantly much less complicated than what Kano went through to put an LS6 onto his truck, whether it was the combination of parts/years or just ****-luck I'm not sure
This is my story:
First and foremost: The reason I attemped this was was purely for asthetics....I wanted a manifold that was good looking, I never expected or even cared about a power difference. I will state that I did take a low-end torque hit from the manifold, this WAS before my heads/cam swap though so if I ever decide to do the swap back to the LS1 I'll bet I don't see a power loss
Parts I had to buy:
Speartech Idler Pulley Relocation Bracket: $75
90º Whipple Billet Aluminum radiator hose elbow $26
Thats it !!!
How I went about swapping:
The first problem I ran into was that the truck injectors are shorter than the f-body injectors so I had to figure out a way to mount the fuel rails....to do this I cut down the injector rail mounting posts .5" with a Dremel, I re-drilled the inside of the posts to accept the threaded brass inserts that were in the top part of the posts that I cut off (I cut them out of the plastic with the dremel) and then drove the insets back into the posts with a ball-peen hammer, The .5" I cut off wasn't exactly the length difference between the two injectors so I used small brass washers as shims to space the rails back up perfectly. I didn't run into the problem Kano had with the truck injectors not fitting into the manifold, mine dropped right in.
Second was the fuel crossover....I just stuck with the truck crossover, it was stupid looking but functional, I eventually planned on having a custom one bent up but ended up removing the manifold before I got around to it.
We've all figured out by now that the truck waterpump and the LSx manifold don't work together because of the outlet location of the waterpump, my solution was to buy the 90º outlet that Whipple sells for their supercharger kits, I cut down the outlet of the waterpump down to about .75" tall and flared the end with a pair of pliers (not pretty but effective for keeping the hose on), I butted the cut-down outlet and the 90º elbow together and used a piece of radiator hose and two clamps to hold them together (this is still on the truck as it was non-reversible). This cleared the cable driven TB I have by only about .020" but it DID clear and didn't rub at all so I was happy with the end result.
The fan.....I thought this was going to be a problem because I still have the mechanical fan on the truck (I live in the hottest place in the western hemisphere, I NEED to know my fan will ALWAYS work), as it turned out the factory intake tubing cleared the fan....certainly not by much (*maybe* .030") but again it DID clear and didn't touch under hard acceleration so I was happy.
Kano ran into problems with the PCV line from the pass. side valve-cover not having any place to plug into on the LS6 manifold, the '98 LS1 I have has a brass tube coming off the side of the intake in the same place as the truck manifold....I used that
The EGR WAS a pain in the *** to do....the trucks EGR pipe WILL work but you have to be extremely careful in bending it to meet up with the top-mounted opening in the LS1 manifold, it DOES work, I PROMISE, you just have to be PATIENT while bending the pipe.....it took me almost an hour of VERY SLOW bending to get it to line up
I re-used the factory gaskets....in fact I've had the manifold off 4 times and I'm still on the factory gaskets (and NO leaks !!)
I never bothered to hide the harness.....It was one of these "I'll get around to it eventually" things and eventually never came.
The relocation bracket was a no-brainer......I bolted it in and bought a new longer belt (sorry...I don't remember the length but it and the relocation bracket are still on the truck so I can get the part number at some point if I remember to)
As for making it all work together.....I installed all of it and it started the truck...it worked the first time
I ended up removing the manifold after about 6 months because I was having all kinds of tuning nightmares due to a crack on the side of the manifold where the top and bottom half were mated together....I'm pretty certain I caused this crack when the shelf that I had the manifold sitting on in my garage collapsed and the manifold bounced across the floor. At the time it was easier for me to just stick the truck manifold back on then to find another LS1 manifold.
There's my story...I'm sticking to it
Last edited by Yelo; 03-01-2006 at 11:28 PM.
03-01-2006, 11:10 PM
#14
Truck addict
Thread Starter
Join Date: Apr 2003
Location: Ocean Springs, MS
Posts: 6,559
Likes: 0
Received 0 Likes
on
0 Posts
thanks for posting. a little work is involved but it is doable and for under 200 bucks from what i can see. granted you have to leave a little money on the table for the incidentals. how was the top end once you got it on. or was the tuning problem keeping you from fully enjoying it.
03-02-2006, 12:00 AM
#15
FormerVendor
iTrader: (3)
Join Date: May 2002
Location: Reseda, CA
Posts: 1,853
Likes: 0
Received 0 Likes
on
0 Posts
A timely topic indeed. Great points everyone. 
I've recently recieved several truck intakes including a 90mm SSR. I'm beginning to gather some flow data on these intakes and will post up as soon as I can. Please bear with me just a bit as we're in the midst of racing season and every job in the shop is in a maximum hurry. I hope to get some good comparison data over the next couple of weeks.
My observation of the truck intakes is that major high flow restrictions exist in the transition from the flow tube located behind the throttle body and the upper plenum which feeds the runners. In the case of the front 4 cylinders, high flowing air heading to the back of the manifold must negotiate a 180º turn and head towards the front of the engine. This increases the part throttle torque and makes the pedal response crisp do to the long flow passage. However at higher flow rates, the air simply cannot maneuver through all the turns quickly enough to fill the cylinders as needed. Think dual plane intakes on the Gen 1 Chevy. Good low end torque and pedal response but lacking high rpm airflow capability. Also think about the car intakes as a single plane style intake. Less low end torque and better high rpm power. I won't go into the sound frequencies discussion here..........
I think I'll find after flow testing the intakes that individually the runner doesn't hurt the port flow significantly, but collectively they can hurt quite a bit. I'm also going to compare an LS6 intake on the same ports at the same time. I'm thinking about making a fixture to bolt the intake runners directly onto the flow bench test orifice in attempt to pull a greater pressure drop in the runner and plenum.
As far as aftermarket intakes are concerned, I would suggest all members contact the various manifold manufacturers and let them know that you'd like see them make a performance intake for our trucks. I'm doing what I can, but it's going to take a louder voice to get the message out. Posting on these forums is also a great way to express your sentiments. You have no idea who all watches these boards.........
That's it for me for the moment.........stay tuned.
Richard
I've recently recieved several truck intakes including a 90mm SSR. I'm beginning to gather some flow data on these intakes and will post up as soon as I can. Please bear with me just a bit as we're in the midst of racing season and every job in the shop is in a maximum hurry. I hope to get some good comparison data over the next couple of weeks.
My observation of the truck intakes is that major high flow restrictions exist in the transition from the flow tube located behind the throttle body and the upper plenum which feeds the runners. In the case of the front 4 cylinders, high flowing air heading to the back of the manifold must negotiate a 180º turn and head towards the front of the engine. This increases the part throttle torque and makes the pedal response crisp do to the long flow passage. However at higher flow rates, the air simply cannot maneuver through all the turns quickly enough to fill the cylinders as needed. Think dual plane intakes on the Gen 1 Chevy. Good low end torque and pedal response but lacking high rpm airflow capability. Also think about the car intakes as a single plane style intake. Less low end torque and better high rpm power. I won't go into the sound frequencies discussion here..........
I think I'll find after flow testing the intakes that individually the runner doesn't hurt the port flow significantly, but collectively they can hurt quite a bit. I'm also going to compare an LS6 intake on the same ports at the same time. I'm thinking about making a fixture to bolt the intake runners directly onto the flow bench test orifice in attempt to pull a greater pressure drop in the runner and plenum.
As far as aftermarket intakes are concerned, I would suggest all members contact the various manifold manufacturers and let them know that you'd like see them make a performance intake for our trucks. I'm doing what I can, but it's going to take a louder voice to get the message out. Posting on these forums is also a great way to express your sentiments. You have no idea who all watches these boards.........
That's it for me for the moment.........stay tuned.
Richard
03-02-2006, 03:58 PM
#16
I am curious to see what happens in the next few weeks/months with Richards test data and Kano's swap results. I never though the truck intake was that much of a restriction untill I put my new setup (h/c LS1) on the dyno two weekends ago. I noticed my torque curve peaked ~4700rpm, sorta flatlined then took a nose dive at 5K. Ironicly the horsepower was ~340 at peak torque and ~365 at 5K. The hp curve was very smooth and linear up to the 5K mark then suddenly got very choppy then peaked at 5900. I started doing a little reasearch and it seems that I am following a trend with the other larger displacement, head and/or cam motors still running the truck intake. I too would like to see an aftermarket bolton solution but unfortunately I don't think we will see that anytime soon.
