*General* FAST LSXr 102 thread
Also, most of the older 90 and 92 designs had #7 and #2 intake runners slightly compromised by an obtrusion in the roof of the port they they cast there due to some folks thinking it would be better in boosted applications. Seriously that was a mistake as it did nothing to improve the integrity of the manifold but it did slightly impede airflow in both of those two cylinders.
This was massaged flush and then 5 minute epoxied because it breaks through, then sanded smooth again...Also i made sure the alignment was optomized by shimming the intake with thicker .200 thick viton watercut gaskets...
So my delima now is how much will the 102 really help on my car after i have already made these improvements that most skip or dont want to tackle...
, i am hoping the 102 fits just as bad as the 92 did so i can capture that gain too...also most run these 102 setups into a lid which will only flow around an equivalent perfect orifice size of 84mm...that is why almost everyone doesnt see a gain going from a 92mm tb to a 102mm tb or even a 85mm maf to a 100mm maf...The major restriction is the lid now...
Decisions decisions...
I wonder how much CFM a 78,85,100 MAF can flow. The same with a 78,90,92,102 T/B
If all an engine is an air pump, it comes down to numbers. If a 85 MAF can support 800hp(this is for argument sake) then why would you go bigger for an engine that is making 450rhwp? Is anyone else see my line of thinking?
I guess it comes down to what part is the most restrective.
It's late. I have been drinking. Take it for what it is.
If all an engine is an air pump, it comes down to numbers. If a 85 MAF can support 800hp(this is for argument sake) then why would you go bigger for an engine that is making 450rhwp? Is anyone else see my line of thinking?
I guess it comes down to what part is the most restrective.
It's late. I have been drinking. Take it for what it is.
You have to look beyond flow numbers. Think about velocity. If we all ran mods based on solely flow numbers we wouldn't get very far. Does it make sense if you are running a 102TB to neck it down to 3.5 inches and then back down to 3 for a 78mm lid opening? if we all modded like that we would have LS6 intakes with stock lids/MAFs on H/C cars because the LS6 can flow the CFM of the heads. Its the same on LT1s. Everyone who thinks they know says a bigger TB on anything less than a stroker is useless when in reality gains are to be had everywhere
Here is something you guys can play around with
CFM = 4005 * (delta p)^.5 * area / 144 (This formula assumes perfect orifice plate)
area is (in^2)
delta p is ( inches h2O)
A 346 with 100% VE is close to 100cfm per 1k rpm...So at 6.5K the engine will need 650CFM...
CFM = 4005 * (delta p)^.5 * area / 144 (This formula assumes perfect orifice plate)
area is (in^2)
delta p is ( inches h2O)
A 346 with 100% VE is close to 100cfm per 1k rpm...So at 6.5K the engine will need 650CFM...
Thread Starter
Joined: Apr 2005
Posts: 4,085
Likes: 1
From: N. Falmouth MA
I'm gonna quote Tony from a couple of other threads....
As far as some of these other "tests" that people have done with the 102 that show a "loss of power" I always wonder.. Do they just swap intakes and pull? If so, no wonder they lost power, things have to be adjusted. What? I don't know, but I know it should be tuned to get the most out of that added air flow.
Sometimes I also wonder if people are following the procedures outlined in the book/manual when it comes to disassembly/reassembly of the intake and runners. For instance, when I reassembled my 102, I did as the book said and use a cut down percentage of soap and water to reinstall the runners, used a small dab of RTV sealant at the back and torqued the top "shell" bolts in sequence to the proper torque (70-89 in/lbs.... I did 79 in/lbs and even THAT felt pretty tight.)
A lot to consider when reading some of these "reviews" on various Performance magazines and/or publications. Possible bias? I question everything anyway. I've gotten burned a couple times on parts that I didn't look into that turned out to be a waste.
And as far as the lids being a restriction, I've been wondering about running an LT1 style CAI. Just grab a polished radiator cover and plum the CAI over to the LT1 location. I dunno on this one.
OK...this thread is pretty funny talking about nothing....LOL
Guys...
When we are discussing fuel injected applications.....the size of the plenum and the opening or the TB (size) will have zero effect on "low end" power.
This is old school thinking stemming from the very real and often practiced applications where too large a carb might have been bolted on a particular engine combination.
The problem stemming from the fact the large carb slowed the airspeed down enough in the venturi's of the main body to negatively effect the carb atomization and therefore hurt power, torque, fuel economy, and responsiveness until enough RPM was generated to allow the carb to become more effective again (guys older than 45 will be nodding their heads up and down right now while reading this!).
We aren't atomizing fuel here folks....thats handled by the injectors and the real meat and potatoes of manifold design (runner length, shape, and taper) hasn't changed much from the 90, 92 or 102.....its very similar but the 102 does have a superior shaped runner (although the length is very similar), is slightly taller, and ultimately flows more, especially when properly ported.
Yes....a FAST 102 can flow more than a 280 CFM head but thats always the case with a really good intake....ideally you want ALOT of headroom when selecting a manifold so when you bolt it in front of your heads it flows more net to the cylinder with the ultimate situation to not hurt the port any more than placing a radius plate in front of it. Thats pure theory unless we are discussing extremely optimized straight shot tunnel ram style manifolds.
I can port a Gen I single plane intake and make it flow 400 CFM.....when you place it in front of a 300 CFM intake port that port still loses 20 CFM which is very good all thing considered. Take the same intake unported by me that still flows way more out of the box than the 300 CFM intake port in question (say the intake flows 360 CFM out of the box) and now you may only see 265 CFM when placed in front of the head because it hurt the net flow more.
INTERNET MYTH #1 .....My 102 Fast is too big for my 346
Wrong....its a better designed intake thats going to allow more air to pass thru the intake ports and be mixed with more precisely atomized fuel from your injectors.
INTERNET MYTH #2....Its already big....you dont need to port it (or it might hurt the bottom end).
Also wrong....at least when ported properly. Once again it simply makes a good piece even better but I would be the first to admit that on a marginal set of head the gains from the work would be less as well. The better the heads, the more aggressive the RPM, displacement, etc. the more that ported 102 is going to pay you in spades.
The larger the restriction the intake manifold becomes....the better your results will be when you swap to the better intake.
If your still questioning anything lets get it handled now and please refer other people back to the answers when we see the same questions and bad information in other threads....I wish I had a nickel for the guys convinced their inaccurate theories are accurate....LOL
The ONLY potential negative to the 102 design...well besides the cost of admission with the rails etc.....is the TB (airblade) is so large it can create drivability challanges with the tune but its a much easier deal on a cable operated 102 with an IAC motor. ALso, it tends to be extremely responsive which I personally like, however some have complained its too responsive (on/off) and they have to get used to driving it. No big deal in my book....
Hope this helps!
-Tony
Guys...
When we are discussing fuel injected applications.....the size of the plenum and the opening or the TB (size) will have zero effect on "low end" power.
This is old school thinking stemming from the very real and often practiced applications where too large a carb might have been bolted on a particular engine combination.
The problem stemming from the fact the large carb slowed the airspeed down enough in the venturi's of the main body to negatively effect the carb atomization and therefore hurt power, torque, fuel economy, and responsiveness until enough RPM was generated to allow the carb to become more effective again (guys older than 45 will be nodding their heads up and down right now while reading this!).
We aren't atomizing fuel here folks....thats handled by the injectors and the real meat and potatoes of manifold design (runner length, shape, and taper) hasn't changed much from the 90, 92 or 102.....its very similar but the 102 does have a superior shaped runner (although the length is very similar), is slightly taller, and ultimately flows more, especially when properly ported.
Yes....a FAST 102 can flow more than a 280 CFM head but thats always the case with a really good intake....ideally you want ALOT of headroom when selecting a manifold so when you bolt it in front of your heads it flows more net to the cylinder with the ultimate situation to not hurt the port any more than placing a radius plate in front of it. Thats pure theory unless we are discussing extremely optimized straight shot tunnel ram style manifolds.
I can port a Gen I single plane intake and make it flow 400 CFM.....when you place it in front of a 300 CFM intake port that port still loses 20 CFM which is very good all thing considered. Take the same intake unported by me that still flows way more out of the box than the 300 CFM intake port in question (say the intake flows 360 CFM out of the box) and now you may only see 265 CFM when placed in front of the head because it hurt the net flow more.
INTERNET MYTH #1 .....My 102 Fast is too big for my 346
Wrong....its a better designed intake thats going to allow more air to pass thru the intake ports and be mixed with more precisely atomized fuel from your injectors.
INTERNET MYTH #2....Its already big....you dont need to port it (or it might hurt the bottom end).
Also wrong....at least when ported properly. Once again it simply makes a good piece even better but I would be the first to admit that on a marginal set of head the gains from the work would be less as well. The better the heads, the more aggressive the RPM, displacement, etc. the more that ported 102 is going to pay you in spades.
The larger the restriction the intake manifold becomes....the better your results will be when you swap to the better intake.
If your still questioning anything lets get it handled now and please refer other people back to the answers when we see the same questions and bad information in other threads....I wish I had a nickel for the guys convinced their inaccurate theories are accurate....LOL
The ONLY potential negative to the 102 design...well besides the cost of admission with the rails etc.....is the TB (airblade) is so large it can create drivability challanges with the tune but its a much easier deal on a cable operated 102 with an IAC motor. ALso, it tends to be extremely responsive which I personally like, however some have complained its too responsive (on/off) and they have to get used to driving it. No big deal in my book....
Hope this helps!
-Tony
Honestly that's a scary quote....(air "stalling" in the intake runners)
Even at idle you have eight pistons 4" across moving vertically close to the same depth at 6-7 times per second (just counting the "intake stroke" in the four cycle engine, not the power stroke)....trust me there is no air "stalling"....its moving thru that plenum at a pretty good clip (because there are eight cylinders pulling from the plenum) and moving thru the runners at a reasonably brisk pace as well. Start turning some RPM's and look out....you guys would be amazed and how much airflow is really moving thru only a 500 HP engine combination. A 300 CFM intake port @ 28" depression will suck you hand to that head (if you get close enough) with enough force to hurt you and that doesn't even represent whats really going on when an engine is at full song.
The good thing about the Internet is the plethora of information available to digest.....the bad thing about the Internet.....yes you guessed it....the plethora of information available to digest.
You need to be selective about who's theories and opinions you might latch on to....
I have seen so much bad info "parroted" from one source to the next its crazy.....
Always verify the accuracy of the source in question....whether discussing engines or which electric razor might work the best.
I love researching things on the Net but I have a pretty good nose for what info might be accurate and what info might not be....comes with age I think though
-Tony
Even at idle you have eight pistons 4" across moving vertically close to the same depth at 6-7 times per second (just counting the "intake stroke" in the four cycle engine, not the power stroke)....trust me there is no air "stalling"....its moving thru that plenum at a pretty good clip (because there are eight cylinders pulling from the plenum) and moving thru the runners at a reasonably brisk pace as well. Start turning some RPM's and look out....you guys would be amazed and how much airflow is really moving thru only a 500 HP engine combination. A 300 CFM intake port @ 28" depression will suck you hand to that head (if you get close enough) with enough force to hurt you and that doesn't even represent whats really going on when an engine is at full song.
The good thing about the Internet is the plethora of information available to digest.....the bad thing about the Internet.....yes you guessed it....the plethora of information available to digest.
You need to be selective about who's theories and opinions you might latch on to....
I have seen so much bad info "parroted" from one source to the next its crazy.....
Always verify the accuracy of the source in question....whether discussing engines or which electric razor might work the best.
I love researching things on the Net but I have a pretty good nose for what info might be accurate and what info might not be....comes with age I think though
-Tony
As far as some of these other "tests" that people have done with the 102 that show a "loss of power" I always wonder.. Do they just swap intakes and pull? If so, no wonder they lost power, things have to be adjusted. What? I don't know, but I know it should be tuned to get the most out of that added air flow.
Sometimes I also wonder if people are following the procedures outlined in the book/manual when it comes to disassembly/reassembly of the intake and runners. For instance, when I reassembled my 102, I did as the book said and use a cut down percentage of soap and water to reinstall the runners, used a small dab of RTV sealant at the back and torqued the top "shell" bolts in sequence to the proper torque (70-89 in/lbs.... I did 79 in/lbs and even THAT felt pretty tight.)
A lot to consider when reading some of these "reviews" on various Performance magazines and/or publications. Possible bias? I question everything anyway. I've gotten burned a couple times on parts that I didn't look into that turned out to be a waste.
And as far as the lids being a restriction, I've been wondering about running an LT1 style CAI. Just grab a polished radiator cover and plum the CAI over to the LT1 location. I dunno on this one.
Last edited by bayer-z28; Feb 26, 2011 at 09:03 AM.
^ take off your lid and look down the snout and you will see why it only flows around a 84mm equivalent size...1/4 of the flow is blocked and necked down to to the way it is made to fit under a stock hood...
Now the question becomes what does 1kpa of vacuum translate into hp gain...and for this I cannot find an answer...so it looks like I will be doing some dyno/track testing...might be worth nothing, might be worth 5hp???
Now the question becomes what does 1kpa of vacuum translate into hp gain...and for this I cannot find an answer...so it looks like I will be doing some dyno/track testing...might be worth nothing, might be worth 5hp???
This is good to know, but what alot of us stock internal build guys are wondering is if the 102 is overkill for us. I have yet to see anyone slap a 102 on a stock h/c car and show proven dyno and race track results. If anyone has, please point me in the right direction.
Is it worth it for us to shell out the added cost to run a 102? Do we even have the potential with stock heads and cam to utilize the added flow of the 102?
Is it worth it for us to shell out the added cost to run a 102? Do we even have the potential with stock heads and cam to utilize the added flow of the 102?
This customer knew he was going to do heads soon and wanted the benefit of the better intake beforehand figuring it could only help, even if it was just a little. We were both pretty pleased....IMO if I helped him with a ported 102 on the same combo it may have been a couple of ponies better....only because the ported 92 already had the stock heads more than covered. Once again....to see the BIG gains, a better cylinder head is always warranted but none the less even with stock heads (and a stock cam for that matter), there is still a difference thats notable. Instead of seeing a 25 HP bump you may only see half of that but the entire curve is picked up nicely and the difference in throttle response would be tremendous (honestly thats one of the perks of this kind of swap that makes it worth the money in and of itself....talk to others who have done it and see if anyone regretted the move)
My advice is make sure you use a good tuner....the problem with that is every tuner thinks they are good....LOL....but the reality is only a small percentage really are. And what separates a really good tuner from an average one is their ability to dial in all the drivability issues of the tune. Making big power is easy.....hell I can do that with my laptop and HP tuners assuming my car is parked on a chassis dyno at the time. Getting the idle nailed down, the part throttle transitions, and overall drivability down is far more challenging. Anyway....this is a topic worthy of its own thread so I will leave it at that.
Guys....the FAST isn't too big....its just too expensive
BUT....if you want to get all your combo has to offer consider saving up and investing in one....and if your really looking to swing for the fences save up a little more and have me port it for you, it close to doubles the gains from the swap for a lot lower percentage invested when the smoke clears (invest 25% more to almost get 100% more output!).
Cheers,
Tony
Last edited by Tony Mamo @ AFR; Feb 26, 2011 at 02:32 PM.
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Verdad Gallardo Seriously though alot of the gains from the 102 are not from the size of the hole in the front. Better runner design and construction, a better vantage point of the injector aimed at the short turn of the intake port, taller runners (hence the occasional fitment issues on some C5 Vettes)....assuming none of this changes going to a larger opening would yield marginal if any gains. A 102 flows in the neighborhood of 2000 CFM's.....more than double the airflow requirement most of the engines these manifolds are perched on.
My guess is this is the final configuration of this manifold style and they will likely ride that wave for quite awhile....
-Tony
Thread Starter
Joined: Apr 2005
Posts: 4,085
Likes: 1
From: N. Falmouth MA
^ Yeah really! Under the cowl! 
SLIGHT PROBLEMS
1: The MAP is hitting the firewall. I'm 1/4-1/2" from being able to bolt it down. It will still too tight for me to be happy w leaving it there. I WAS gonna run it up front, but I already drilled the darn hole for the back one.
2: How the HELL do I get a tq wrench in here?!?! I have a pretty small tq wrench and I am still wondering if I'll get it back there. (Didn't even try. I'm tired and hungry) I did the LS6 PCV today, so after cleaning everything up and prepping, I slid the intake in, connected the 2 lines and MAP and eased it back into place (as far is it would go without breaking anything.)
And on the funny side... I was cutting the clearance for the valley cover and the evil *** El Es Juan ate my new Dremel! Was using it for five minutes and I noticed some smoke.. No the rags aren't on fire. Stopped... Didn't smell like Ozone, just stinking plastics and brushes maybe. ***** is STILL hot. Wasn't burning my hand tho. Switched to my Craftsman Dremel and the hand extension to finish the job.
Parts/install ****:
SLIGHT PROBLEMS
1: The MAP is hitting the firewall. I'm 1/4-1/2" from being able to bolt it down. It will still too tight for me to be happy w leaving it there. I WAS gonna run it up front, but I already drilled the darn hole for the back one.
2: How the HELL do I get a tq wrench in here?!?! I have a pretty small tq wrench and I am still wondering if I'll get it back there. (Didn't even try. I'm tired and hungry) I did the LS6 PCV today, so after cleaning everything up and prepping, I slid the intake in, connected the 2 lines and MAP and eased it back into place (as far is it would go without breaking anything.)
And on the funny side... I was cutting the clearance for the valley cover and the evil *** El Es Juan ate my new Dremel!
Was using it for five minutes and I noticed some smoke.. No the rags aren't on fire. Stopped... Didn't smell like Ozone, just stinking plastics and brushes maybe. ***** is STILL hot. Wasn't burning my hand tho. Switched to my Craftsman Dremel and the hand extension to finish the job.Parts/install ****:
Last edited by bayer-z28; Feb 26, 2011 at 08:06 PM.
They are running out of real estate.....LOL
Seriously though alot of the gains from the 102 are not from the size of the hole in the front. Better runner design and construction, a better vantage point of the injector aimed at the short turn of the intake port, taller runners (hence the occasional fitment issues on some C5 Vettes)....assuming none of this changes going to a larger opening would yield marginal if any gains. A 102 flows in the neighborhood of 2000 CFM's.....more than double the airflow requirement most of the engines these manifolds are perched on.
My guess is this is the final configuration of this manifold style and they will likely ride that wave for quite awhile....
-Tony
Seriously though alot of the gains from the 102 are not from the size of the hole in the front. Better runner design and construction, a better vantage point of the injector aimed at the short turn of the intake port, taller runners (hence the occasional fitment issues on some C5 Vettes)....assuming none of this changes going to a larger opening would yield marginal if any gains. A 102 flows in the neighborhood of 2000 CFM's.....more than double the airflow requirement most of the engines these manifolds are perched on.
My guess is this is the final configuration of this manifold style and they will likely ride that wave for quite awhile....
-Tony
Flow is just the pressure difference between one chamber to the next over a certain orifice size...This is then multipied by a correction factor depending on the orifice geometry...
You have to have a very large engine to see any gains from a 92mm TB to a 102mm TB on the FAST intake. People just want to say they have the biggest, so they buy the 102mm TBs.
Thread Starter
Joined: Apr 2005
Posts: 4,085
Likes: 1
From: N. Falmouth MA
^ Like Tony said, the 102 itself is just all around a better design. The way I see it, the TB opening has only a little to do with it. I still have yet to get mine tuned (or running.. Still need a TB and to decide on how to duct this.. Lid or CAI) I was quite torn between the 92 and 102 about a month ago. Couldn't decide till I saw the flow differences. Only about 5-7 cfm better on 243 heads, but still. It shows that there is something indeed different. (stock vs stock)
How are you getting 2000CFM, Just wondering becuase 2000CFM through a 102mm opening gives a pressure drop or vacuum in the manifold of 32" h20 or 8kPa of vacuum...since atm is 101kpa the map would be reading around 93kpa...which is a definite restriction...that is why i never understood why people say a tb or maf can flow this amount? what is the standard pressure drop you are using to compare these components to get a corresponding CFM value?
Flow is just the pressure difference between one chamber to the next over a certain orifice size...This is then multipied by a correction factor depending on the orifice geometry...
Flow is just the pressure difference between one chamber to the next over a certain orifice size...This is then multipied by a correction factor depending on the orifice geometry...
I threw that number out there quickly earlier knowing it would be close....after just doing some math based on its actual CSA I calculate closer the 1850 CFM is probably more accurate.
Either way the point I made is valid....from here there is very little to be gained from opening up the hole....only changing runner shape, length, or CSA is going to effect the power curve from this point moving forward.
-Tony
I was worried about the map thats why I posted earlier in this thread that I relocated mine to the front hole. I would take it back off and seal the back hole and relocate. Any kind of engine rock and I can't imagine it not breaking.
There was another post on the boards with in the last month of someone having the same problem with the MAP sensor. I think they turned it the other way????? and it fixed it. Not having installed one yet I don't know. I think I am just going to put in on top even though it's not as clean of look IMO.
Glad to see some good posts in this thread.
I get what Tony is saying about the runner length and design of the intake. If you take an old SBC and have three different intakes; lets say a performer, vic jr and a super vic, all three use ABOUT the same opening for the carb flange, but each one has different power out puts and RPM ranges.
Am I looking at this right?
Which begs my next question; has FAST released any different runners yet for the 102? I remember that being a selling point in the past but i have yet to see different runners.
IMO, as limited as my knowledge is, I wouldn't think that a stock 346 wouldn't use the same runners as a 427+ CID engine.
I know that we aren't mixing fuel/air anymore but am I flawed in this line of thinking?
Glad to see some good posts in this thread.
I get what Tony is saying about the runner length and design of the intake. If you take an old SBC and have three different intakes; lets say a performer, vic jr and a super vic, all three use ABOUT the same opening for the carb flange, but each one has different power out puts and RPM ranges.
Am I looking at this right?
Which begs my next question; has FAST released any different runners yet for the 102? I remember that being a selling point in the past but i have yet to see different runners.
IMO, as limited as my knowledge is, I wouldn't think that a stock 346 wouldn't use the same runners as a 427+ CID engine.
I know that we aren't mixing fuel/air anymore but am I flawed in this line of thinking?