Yet another Intake Manifold Thread
05-04-2007, 07:40 PM
#1
LS1 Tech Veteran
Thread Starter
iTrader: (1)
Join Date: Oct 2003
Location: Wichita, Ks
Posts: 1,172
Likes: 0
Received 0 Likes
on
0 Posts
New Data Comparing Intake Manifolds
There have been several threads about the truck intake manifold versus the LS1/LS6/FAST manifolds. I’ve been intrigued by the subject for several years and I’ve done some research so I’m starting yet another thread that I hope will be informative.
As many of you may recall, Chevy High Performance (CHP) Magazine did a comparison of these manifolds (plus one other) in July of 2004 (Ro McGonegal – text and Henry De Los Santos – photography). This issue compared these manifolds plus a Weiland/Lingenfelter manifold on 5.7 L LS1 crate engine with a 10.25:1 compression ratio, long tube headers with no mufflers or cats and no accessories (water pump, power steering, alternator, or air conditioning compressor) to rob any power from the dynamometer. This first round of tests used the stock cam (200°/203° @ .050” duration and .500” gross valve lifts for intake & exhaust), rockers, and pushrods according to the article. The dyno testing was conducted by the fine folks at Westech Performance Group who probably do more testing of this type than any other facility. This round of testing was accompanied by a graph comparing the five intakes with the same engine. OK, nothing new so far, just a review.
To continue the review, in August 2004, Henry De Los Santos did the follow-up article (text and photography) that tested all of the intakes except the Weiland/Lingenfelter with three progressively bigger aftermarket cams. In addition, they changed the valve springs to Comp Beehives (I assume P/N: 26918 probably with titanium retainers) and they went to the Comp roller tip rockers (1.75:1 ratio which adds 3% to the advertised valve lift at 1.7:1). Also, I will assume they used hardened pushrods although the article didn’t mention this aspect. CHP published a side bar with the results of each cam being shown as max torque, max HP and the engine speed in RPM’s for each manifold. This is good information, but not enough to satisfy the engineer in me.
I kept hoping that CHP would do some sort of follow-up article with graphs of the four manifold/three cam comparison, but it never came to be (many stories compete for space in publications). Then in 2005, I decided to write Henry De Los Santos an email and request the graphs. It took a few phone calls and some more emails (Henry’s a busy guy), but we did hook up and he was very kind to send me the data in a file type known as .csv for comma separated values. This type of file data can be easily imported into any spread sheet software so I converted it into Excel files and created the graphs you see below. Hopefully, these graphs will help people interested in any of these manifolds make some informed decisions as to the best course of action for their application.
It appears to me that at wide open throttle (WOT), the truck/LS6/FAST all better the HP and torque of the LS1 through most of the operating range. Further, it appears that the truck and the LS6 hang right in there with the FAST until around 430 HP and a bit over 5,000 RPM’s. Then the FAST and LS6 begin to ease away from the truck manifold. The LS6 pretty well keeps pace with the FAST manifold for a few hundred RPM's and a few more HP before the FAST manifold eases away from the LS6. HP is directly related to mass air flow and I believe that that is mainly what we are seeing borne out here. The graphs just help quantify the differences.
One thing that the graphs do not show and that is the effectiveness of the manifold in part throttle situations. I highly suspect that the truck manifold beats all the others in part throttle torque hands down. According to Chris Endres’ book Chevy LS1/LS6 Performance, the truck manifold’s plenum volume is smaller (4 L versus 5.06 L for the LS1 and 5.19 L for the LS6) and the truck intake runner volume is less (.513 L versus .536 L for the LS1 and .541 L for the LS6) while the runner lengths are 263 or 262 mm for all versions). The reduction in the truck’s plenum and runner volumes increase velocity in the same way a small runner intake does on a cylinder head. All of these things contribute to good torque production at part throttle.
I especially appreciate Henry De Los Santos for sending me the data for without that information, I never could have created the graphs. Hopefully, this information will help quantify the differences in the manifolds by adding some more data to the discussion.
All my best,
Steve
As many of you may recall, Chevy High Performance (CHP) Magazine did a comparison of these manifolds (plus one other) in July of 2004 (Ro McGonegal – text and Henry De Los Santos – photography). This issue compared these manifolds plus a Weiland/Lingenfelter manifold on 5.7 L LS1 crate engine with a 10.25:1 compression ratio, long tube headers with no mufflers or cats and no accessories (water pump, power steering, alternator, or air conditioning compressor) to rob any power from the dynamometer. This first round of tests used the stock cam (200°/203° @ .050” duration and .500” gross valve lifts for intake & exhaust), rockers, and pushrods according to the article. The dyno testing was conducted by the fine folks at Westech Performance Group who probably do more testing of this type than any other facility. This round of testing was accompanied by a graph comparing the five intakes with the same engine. OK, nothing new so far, just a review.
To continue the review, in August 2004, Henry De Los Santos did the follow-up article (text and photography) that tested all of the intakes except the Weiland/Lingenfelter with three progressively bigger aftermarket cams. In addition, they changed the valve springs to Comp Beehives (I assume P/N: 26918 probably with titanium retainers) and they went to the Comp roller tip rockers (1.75:1 ratio which adds 3% to the advertised valve lift at 1.7:1). Also, I will assume they used hardened pushrods although the article didn’t mention this aspect. CHP published a side bar with the results of each cam being shown as max torque, max HP and the engine speed in RPM’s for each manifold. This is good information, but not enough to satisfy the engineer in me.
I kept hoping that CHP would do some sort of follow-up article with graphs of the four manifold/three cam comparison, but it never came to be (many stories compete for space in publications). Then in 2005, I decided to write Henry De Los Santos an email and request the graphs. It took a few phone calls and some more emails (Henry’s a busy guy), but we did hook up and he was very kind to send me the data in a file type known as .csv for comma separated values. This type of file data can be easily imported into any spread sheet software so I converted it into Excel files and created the graphs you see below. Hopefully, these graphs will help people interested in any of these manifolds make some informed decisions as to the best course of action for their application.
It appears to me that at wide open throttle (WOT), the truck/LS6/FAST all better the HP and torque of the LS1 through most of the operating range. Further, it appears that the truck and the LS6 hang right in there with the FAST until around 430 HP and a bit over 5,000 RPM’s. Then the FAST and LS6 begin to ease away from the truck manifold. The LS6 pretty well keeps pace with the FAST manifold for a few hundred RPM's and a few more HP before the FAST manifold eases away from the LS6. HP is directly related to mass air flow and I believe that that is mainly what we are seeing borne out here. The graphs just help quantify the differences.
One thing that the graphs do not show and that is the effectiveness of the manifold in part throttle situations. I highly suspect that the truck manifold beats all the others in part throttle torque hands down. According to Chris Endres’ book Chevy LS1/LS6 Performance, the truck manifold’s plenum volume is smaller (4 L versus 5.06 L for the LS1 and 5.19 L for the LS6) and the truck intake runner volume is less (.513 L versus .536 L for the LS1 and .541 L for the LS6) while the runner lengths are 263 or 262 mm for all versions). The reduction in the truck’s plenum and runner volumes increase velocity in the same way a small runner intake does on a cylinder head. All of these things contribute to good torque production at part throttle.
I especially appreciate Henry De Los Santos for sending me the data for without that information, I never could have created the graphs. Hopefully, this information will help quantify the differences in the manifolds by adding some more data to the discussion.
All my best,
Steve
Last edited by Steve Bryant; 05-05-2007 at 08:12 AM. Reason: Changed Title
05-04-2007, 09:21 PM
#3
17,16,15,14,13,12,11 Drvr
iTrader: (10)
Join Date: Aug 2003
Location: Mont Belvieu, Texas
Posts: 6,713
Likes: 0
Received 0 Likes
on
0 Posts
Well if everyone will notice the same curves for the truck and car intakes, and yes the ls6 intake seems to make more HP over the truck intake, but this is on a ls1 5.7, wish they would or could do it on a 5.3 to see for sure, again great post.
05-05-2007, 09:26 AM
#5
TECH Addict
iTrader: (18)
Join Date: Oct 2003
Location: Northeast, NJ
Posts: 2,373
Likes: 0
Received 0 Likes
on
0 Posts
Thank you for producing graphs with this information, since this is the magazine article started the myth that truck intake is a phenomenal performance piece.
Intersting to note is that the FAST, LS6, and truck intake are producing almost identical amounts of torque which disproves the "you'll loose low end when you switch to a LS6" agrument.
So if we can summarize from these graphs, even an engine with a small cam will benefit from a car intake swap above 5000 rpm with a LS6 swap and even with a FAST 90 setup with hardly any if any at all loss of torque. Engines with bigger cams will see an even greater benefit.
Makes me want to put my LS6 intake up for sale and go right for the FAST 90.
Intersting to note is that the FAST, LS6, and truck intake are producing almost identical amounts of torque which disproves the "you'll loose low end when you switch to a LS6" agrument.
So if we can summarize from these graphs, even an engine with a small cam will benefit from a car intake swap above 5000 rpm with a LS6 swap and even with a FAST 90 setup with hardly any if any at all loss of torque. Engines with bigger cams will see an even greater benefit.
Makes me want to put my LS6 intake up for sale and go right for the FAST 90.
05-05-2007, 11:51 AM
#6
TECH Resident
Join Date: Jun 2005
Location: Taxachusetts
Posts: 810
Likes: 0
Received 0 Likes
on
0 Posts
Mad props to Steve for posting these tests!
It's also very important to remember the weight of the truck when considering this information. Most of the trucks around here are DD's, while there's alot of overlapping information more beneficial true perfomance builds.
Using 425lb/ft as a reference, notice as the cam becomes larger it takes longer to cross that threshold. Basically, using a larger cam with a better flowing intake will create more power which isn't necessarily advantageous for moving the weight of the truck where it normally rolls.
With FI it may not present a problem on the street but I think that NA trucks should really keep an eye out to not over-size their cams. Their only real useful remedy without major tuning hassles would be to match it up with the right (high) stall converter.
Steve, thanks again for the graphs. Now, I know for sure I'll be sticking with my 210-218@116, idleing at 600rpm, with my truck intake. Spray on the way!
It's also very important to remember the weight of the truck when considering this information. Most of the trucks around here are DD's, while there's alot of overlapping information more beneficial true perfomance builds.
Using 425lb/ft as a reference, notice as the cam becomes larger it takes longer to cross that threshold. Basically, using a larger cam with a better flowing intake will create more power which isn't necessarily advantageous for moving the weight of the truck where it normally rolls.
With FI it may not present a problem on the street but I think that NA trucks should really keep an eye out to not over-size their cams. Their only real useful remedy without major tuning hassles would be to match it up with the right (high) stall converter.
Steve, thanks again for the graphs. Now, I know for sure I'll be sticking with my 210-218@116, idleing at 600rpm, with my truck intake. Spray on the way!
Last edited by .T.; 05-05-2007 at 12:18 PM.
05-05-2007, 06:30 PM
#7
i think the gaps in performance between these intakes will tighten with smaller motors. i havent seen any evidence yet that the ls6 intake is benifitial to truck motors. havent seen a cam/head/intake 5.3 or 4.8 yet though either. im still on the sidelines for a 5.3 truck gaining anything with the ls6 intkae.
ive seen 2 dyno's in one day first hand showing that the truck intake didnt "PLUMIT" after 6,000 rpm.
ive seen 2 dyno's in one day first hand showing that the truck intake didnt "PLUMIT" after 6,000 rpm.
Trending Topics
05-05-2007, 11:19 PM
#9
FormerVendor
iTrader: (3)
Join Date: May 2002
Location: Reseda, CA
Posts: 1,853
Likes: 0
Received 0 Likes
on
0 Posts
Thank you Steve for following up and organizing this data.
It appears that the jump from the 222º to 232º cam doesn't change the rpm that peak torque and peak hp occur at. I guess the larger cam steps beyond the design limits of the LS6 and FAST intake. Also interesting to see that the truck and LS1 intake are nearly identical in power with the largest cam.
The large cam sure makes a hole in the midrange that really narrows up the power band.
I imagine a well built 5.3l, 6.0l or 402 will really tax the truck intake.
Again Steve, thank you for following up on this and helping to shed some more light on the intake issue.
Richard
It appears that the jump from the 222º to 232º cam doesn't change the rpm that peak torque and peak hp occur at. I guess the larger cam steps beyond the design limits of the LS6 and FAST intake. Also interesting to see that the truck and LS1 intake are nearly identical in power with the largest cam.
The large cam sure makes a hole in the midrange that really narrows up the power band.
I imagine a well built 5.3l, 6.0l or 402 will really tax the truck intake.
Again Steve, thank you for following up on this and helping to shed some more light on the intake issue.
Richard
05-06-2007, 12:11 AM
#10
LS1 Tech Veteran
Thread Starter
iTrader: (1)
Join Date: Oct 2003
Location: Wichita, Ks
Posts: 1,172
Likes: 0
Received 0 Likes
on
0 Posts
Once again guys, thanks for the kind words. I had meant to finalize this information and start a thread with this information about a year ago. I never lost interest in the subject, but life's events just got in the way.
The basic issue with all of the intakes is that the factory pieces are all excellent for production vehicles that are operated within or somewhat beyond their design parameters. The FAST manifold improves upon the LS6 which had to be quite an accomplishment for Wilson Manifolds (primary designers of the FAST intake). In addition, the FAST is modular and can be disassembled to really make porting easier.
None of the OEM or aftermarket manifolds are really suited to a significantly modified truck engine that is normally aspirated because a lot of modification has to be done to make any of the car manifolds work on a truck. If a FAST-type design were available that had the throttle body about three inches higher (like the Gen III/IV truck designs), that would be great for big camed trucks designed a blend of street and strip performance. It would also do well for larger displacement engines with more moderate cams.
On another note, I actually think that the truck manifold will work fine for the type of engine that I'm planning to assemble later this summer (even though it's a 408) because I want part throttle torque above all else. However, I'm in a different situation than most folks who want more performance.
I'm interested to see what other observations people have about this subject.
Steve
The basic issue with all of the intakes is that the factory pieces are all excellent for production vehicles that are operated within or somewhat beyond their design parameters. The FAST manifold improves upon the LS6 which had to be quite an accomplishment for Wilson Manifolds (primary designers of the FAST intake). In addition, the FAST is modular and can be disassembled to really make porting easier.
None of the OEM or aftermarket manifolds are really suited to a significantly modified truck engine that is normally aspirated because a lot of modification has to be done to make any of the car manifolds work on a truck. If a FAST-type design were available that had the throttle body about three inches higher (like the Gen III/IV truck designs), that would be great for big camed trucks designed a blend of street and strip performance. It would also do well for larger displacement engines with more moderate cams.
On another note, I actually think that the truck manifold will work fine for the type of engine that I'm planning to assemble later this summer (even though it's a 408) because I want part throttle torque above all else. However, I'm in a different situation than most folks who want more performance.
I'm interested to see what other observations people have about this subject.
Steve