My Vortec Combo disappoints
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Thats cool i saw one of them on pawn stars.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
1938 Chevy "one ton" truck from the forest service. Six cylinder inline splash lubrication system, displacement unknown. It could climb a tree in first and at the piston swapping rpm of 3500 in fourth gear did 45 mph.
That one ton could haul about 4 tons without a problem.
That one ton could haul about 4 tons without a problem.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
You compression ratio is fine! You might want to look at a Comp or Lunati Voodoo cam in the low 220 degree range. I think your restricting your motors potential with the short duration cam especially with a 4 speed manual transmission as performnce under 2500RPM shouldn't be too much of a concern with a manual transmission unless your doing off road 4X4 trails. Your beehives should allow around 0.500 lift but, this should be measured and not assumed. I would pick something like this cam: http://www.lunatipower.com/Product.aspx?id=2325&gid=297
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
1938 Chevy "one ton" truck from the forest service. Six cylinder inline splash lubrication system, displacement unknown. It could climb a tree in first and at the piston swapping rpm of 3500 in fourth gear did 45 mph.
That one ton could haul about 4 tons without a problem.
That one ton could haul about 4 tons without a problem.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
You compression ratio is fine! You might want to look at a Comp or Lunati Voodoo cam in the low 220 degree range. I think your restricting your motors potential with the short duration cam especially with a 4 speed manual transmission as performnce under 2500RPM shouldn't be too much of a concern with a manual transmission unless your doing off road 4X4 trails. Your beehives should allow around 0.500 lift but, this should be measured and not assumed. I would pick something like this cam: http://www.lunatipower.com/Product.aspx?id=2325&gid=297
Race Director
Joined: Oct 2000
Posts: 15,060
Likes: 79
From: central FL, near the beach.
The OP did confess he now doesn't go on the highway.
3.70 or 4.10 is fine around town. It is fun to shift into 2nd WOT and not be speeding! And in my 61, 4.11, i get 15-18 mpg if i go with the traffic flow. Single pattern cams don't send as much fuel out the exhaust. That mpg info isn't in the fine print on those voodoo etc cams with long, loud, exhaust duration.
As far as NOISE, i'm not deaf like mako
so i use earplugs.
3.70 or 4.10 is fine around town. It is fun to shift into 2nd WOT and not be speeding! And in my 61, 4.11, i get 15-18 mpg if i go with the traffic flow. Single pattern cams don't send as much fuel out the exhaust. That mpg info isn't in the fine print on those voodoo etc cams with long, loud, exhaust duration.
As far as NOISE, i'm not deaf like mako
so i use earplugs.
Last edited by Matt Gruber; Jan 19, 2013 at 06:16 AM.
Race Director
Joined: Oct 2000
Posts: 15,060
Likes: 79
From: central FL, near the beach.
More overlap lowers mpg. Sure one could design a cam intended to minimize the effect, but that is not the intent of the newer off the shelf cams. Customers want power, noise(race car sound), lumpy idle, not mpg. At least it is NOT on their list at the time of purchase. After a few fill ups 
Last edited by Matt Gruber; Jan 19, 2013 at 10:03 AM.
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Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
The OP did confess he now doesn't go on the highway.
3.70 or 4.10 is fine around town. It is fun to shift into 2nd WOT and not be speeding! And in my 61, 4.11, i get 15-18 mpg if i go with the traffic flow. Single pattern cams don't send as much fuel out the exhaust. That mpg info isn't in the fine print on those voodoo etc cams with long, loud, exhaust duration.
As far as NOISE, i'm not deaf like mako so i use earplugs.
3.70 or 4.10 is fine around town. It is fun to shift into 2nd WOT and not be speeding! And in my 61, 4.11, i get 15-18 mpg if i go with the traffic flow. Single pattern cams don't send as much fuel out the exhaust. That mpg info isn't in the fine print on those voodoo etc cams with long, loud, exhaust duration.
As far as NOISE, i'm not deaf like mako
so i use earplugs.
Race Director
Joined: Oct 2000
Posts: 15,060
Likes: 79
From: central FL, near the beach.
There are often exceptions, but even the un-exciting SR Torquers didn't need more exhaust duration in that dyno test i often quote. The frequently claimed benefit to more exhaust is, it extends the rpm range. But, how often do we see guys wanting more rpm? For the 270H, comp says max hp at 5800, shift at 6000. Jeff shifts it 6900 wth vortec heads, i've been to 7000 a few times. So how much more is needed, and for what purpose? And your warnings about too much CR, wouldn't less efficient removal of exhaust help tame detonation? Could this be what maxes out your CR at a lower CR then others? Carl Hinkson(engine shop) uses single pattern cams with higher CR STREET engines.
Last edited by Matt Gruber; Jan 19, 2013 at 03:12 PM.
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
There are often exceptions, but even the un-exciting SR Torquers didn't need more exhaust duration in that dyno test i often quote. The frequently claimed benefit to more exhaust is, it extends the rpm range. But, how often do we see guys wanting more rpm? For the 270H, comp says max hp at 5800, shift at 6000. Jeff shifts it 6900 wth vortec heads, i've been to 7000 a few times. So how much more is needed, and for what purpose?
Scoggin Dickey says they made 357 hp @4900 rpm by adding an LT4 Hot Cam, 1.6 ratio rockers (.525/.525 lift 218/228 duration) a 52mm throttle body, and Edelbrock High Flow runners. That seems like an awful lot more cam for the extra 50 hp and it would have a significantly negative effect on gas mileage.
I don't want to change anything else in the TPI other than cam. The stock L98 cam seems pretty mild. I know the stock L98 peak power is at around 4500 rpm and runs out of steam at about 5000. I want my motor to pull to the 6000 rpm redline where I'll shift. Low speed torque is not particularly a concern but gas mileage is. Any thoughts on what would be a good cam for this combo that would produce 325 gross hp or better yet still get good gas mileage?
Race Director
Joined: Oct 2000
Posts: 15,060
Likes: 79
From: central FL, near the beach.
Priya
roller cam or FT, solids ok? or just H?
I'm not any sort of cam designer, so others with similar builds should be given serious consideration. Hopefully they will chime in.
roller cam or FT, solids ok? or just H?
I'm not any sort of cam designer, so others with similar builds should be given serious consideration. Hopefully they will chime in.
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
You've both overlooked my experience with the 3.70 rear and the factory 4 speed and its 2.54 first gear:
So, you're suggesting I start out in the 5 speed's even lower 1.99 second. I'm pretty sure that's a bad idea given how the car reacted with the m21's 2.54 first. No, my 3.70 reared car needs a much lower gear than the factory 2.54. I'm hoping with the 3.37 first in the five speed there will be some wheel spin but I'd bet it won't be excessive with the present 295/50 15 rear tires.
Remember I'm planning on building a similar motor to the OP's and he's complaining about the off the line slow acceleration. I had a 70 Torino with 3.89 rear gears and 22 inch tall tires which is the equivalent of a 4.95 rear gear with 28 inch tall tires such as on the Corvette. With the Torino's 2.78 first that was an overal first gear ratio of 13.76. Did it spin excessively? Yes, but not so much so that it didn't love driving it or was ever tempted to start out in second. It had a 6000 rpm 351 cleveland which didn't produce much power below 2500 rpm but came on real strong at higher rpms. I'm looking to duplicate that motor's performance with my 350.
In the Corvette with its 2.54 first I find I'm revving the motor a lot faster than I'd like and riding the clutch to get it moving from a stop and I find it really annoying to initially get it moving - it needs a lot more gear for my taste. And with the 3.70 gears in my Corvette I'm revving at about 3000 rpm at 60MPH - also very annoying. The .67 5th gear in the Keisler trans brings this down to 2000 rpm, a lot better for crusing and a lot better for gas mileage.
So, no offense guys, but I'm going with my opinion on the five speed, not yours and I think its ideal for my heavy corvette with the planned low torque 325 -350 gross hp 350.
So, you're suggesting I start out in the 5 speed's even lower 1.99 second. I'm pretty sure that's a bad idea given how the car reacted with the m21's 2.54 first. No, my 3.70 reared car needs a much lower gear than the factory 2.54. I'm hoping with the 3.37 first in the five speed there will be some wheel spin but I'd bet it won't be excessive with the present 295/50 15 rear tires.
Remember I'm planning on building a similar motor to the OP's and he's complaining about the off the line slow acceleration. I had a 70 Torino with 3.89 rear gears and 22 inch tall tires which is the equivalent of a 4.95 rear gear with 28 inch tall tires such as on the Corvette. With the Torino's 2.78 first that was an overal first gear ratio of 13.76. Did it spin excessively? Yes, but not so much so that it didn't love driving it or was ever tempted to start out in second. It had a 6000 rpm 351 cleveland which didn't produce much power below 2500 rpm but came on real strong at higher rpms. I'm looking to duplicate that motor's performance with my 350.
In the Corvette with its 2.54 first I find I'm revving the motor a lot faster than I'd like and riding the clutch to get it moving from a stop and I find it really annoying to initially get it moving - it needs a lot more gear for my taste. And with the 3.70 gears in my Corvette I'm revving at about 3000 rpm at 60MPH - also very annoying. The .67 5th gear in the Keisler trans brings this down to 2000 rpm, a lot better for crusing and a lot better for gas mileage.
So, no offense guys, but I'm going with my opinion on the five speed, not yours and I think its ideal for my heavy corvette with the planned low torque 325 -350 gross hp 350.
3.37 with a 3.70 will be some overkill its going to feel like a granny geared 4 speed pickup truck in low gear. You should like the overdrive part of it.
3.37 x 3.70 = 12.46, 5.57 rear x M21 muncie 2.20 = 12.25
Welcome to the world of 31 inch dia. slicks and 9,000 plus rpm.
BFgoodrich 295/50 , 26.65 Dia.
I drove two cars with 26 1/2 dia. street tires bolted on one 4.88 other 5.13, 1rst gear in either one was unusable quickly shift it to second. You should have something simular to about 5.70 rear gears in low. Spinning tires in low will be no problem lol.
Last edited by Little Mouse; Jan 19, 2013 at 04:40 PM.
Race Director
Joined: Oct 2000
Posts: 15,060
Likes: 79
From: central FL, near the beach.
Priya
TPI to 6000? You are dreaming
Talk to the c4 guys! I don't have a clue offhand. Sorry.
Oh wait, there was a c4 guy years ago that put afr heads on a TPI and it was quite a surprise how well it ran w/cam and mods.
That TPI will get good mpg. That is all i know about TPI
TPI to 6000? You are dreaming
Talk to the c4 guys! I don't have a clue offhand. Sorry.
Oh wait, there was a c4 guy years ago that put afr heads on a TPI and it was quite a surprise how well it ran w/cam and mods.
That TPI will get good mpg. That is all i know about TPI
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
I've looked at a number of C4 TPI builds and many of them are running to 6000 or more but all the one's I've looked at are like 400 hp or more and they're running mid to low twelve second quarter miles with their C4's. I haven't found any C4 tpi builds that are of a moderate performance such as I'm after.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Another reason the OP has a doggy ride. It came with a 3.70 4 speed likly a close ratio trans 2.43 1st. that and a 3.36 rear is 8.16 first gear. To get to the optimal 10 to 1 first you need a 4.11. Then highway cruise sucks.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Gonna be hard to get a TPI to pull up that high its the runner length that handicaps it. Will it rev up that high maybe making power there no.
Shoot for something in the low to mid teens most at .050 thats how they run best, gear and converter accordingly.
LT4 cam was meant for a stick with low gears, short runner intake.
Guys use them on the TPI with some success they are not bad just better choices out there.
Shoot for something in the low to mid teens most at .050 thats how they run best, gear and converter accordingly.
LT4 cam was meant for a stick with low gears, short runner intake.
Guys use them on the TPI with some success they are not bad just better choices out there.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
LS4 is not much for a 454 but it still had buckets more torque down low then this lightly modded 350 will ever see. 2.20 low gear with a 3.36 is no drag machine even for a 454 lol.
No wonder why he is dissapointed.