355 mouse vortec powerhouse! long THREAD!!!!
08-13-2008, 06:18 PM
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355 mouse vortec powerhouse! long THREAD!!!!
Hot, Hot, Hot, Part I
An Inexpensive Roller Cam 400hp Small-Block
By Jeff Smith
photographer: Jeff Smith
Face it: Everybody’s looking for The Deal—you know, the 400hp motor for $100. We’re not there yet, but we’re always searching for better ways to build a small-block and we think we’ve stumbled onto one that is plenty hot. The key to a strong engine is the combination of great heads and an excellent camshaft. Improved airflow is usually accompanied by a hefty price tag, but check out this combo: Start with a late-model roller cam 350ci block. Bolt on a set of Vortec iron heads and a GM Performance Parts HOT hydraulic roller cam. Sprinkle on an aluminum GM Vortec dual-plane intake and you have an outstanding combination of all-new parts, with the heads, cam, and intake costing less than $800!
Our pal Tim Moore is building this exact package. But before you dive right into this deal, there are a few important details that you need to know that could save you money. The hinge pin to this plan is an ’88-or-later 350ci roller-cam cylinder block. Chevy put these engines in Camaros, Firebirds, police cars, some Caprices, and ¾-ton truck chassis also used in motor homes. These roller cam blocks differ from earlier blocks in several significant ways.
Block Tech
Starting in ’87, Chevy converted all small-blocks to a one-piece rear-main seal combined with an excellent one-piece oil pan seal. Chevy followed that in ’88 with hydraulic roller cams in most V-8 engines. To accommodate the taller hydraulic roller lifter, Chevy increased the height of the lifter boss. This also required two small cast-in bosses in the middle of the lifter valley to mount the sheetmetal retainer, called the “spider,” which retains each pair of lifters.
All this block information is given for several reasons. The GM Performance Parts HOT hydraulic roller is a great, affordable cam ($175 from Scoggin-Dickey Performance) and begs to be matched with a set of Vortec heads. This OEM-style roller cam is intended to work in ’88-and-later roller cam small-blocks, because it requires a production thrust plate. However, according to our erudite engine enthusiast Kevin McClelland, you can use this cam in an early two-piece rear-main seal block. Trim the ears off the production roller-cam thrust plate and use it as a spacer between the cam gear and the block. Then employ a thrust button to control cam endplay. This will require using aftermarket hydraulic roller tappets, which are more expensive than the factory hydraulic roller tappets. This way, you could use your existing, older two-piece rear-main seal block.
Since Tim was building a whole new motor, he latched onto a used roller cam 350ci short-block that came out of an ’89 Caprice police car. He disassembled it, had the crank machined and the rods rebuilt, and added a set of Federal-Mogul hypereutectic pistons. He also measured the deck height and had the block milled to establish a 0.005-inch piston-to-deck clearance. He also used the inexpensive GM Performance Parts cam drive assembly for the roller cam that is a screamin’ deal at $40. Tim re-used the stock hydraulic lifters, oil pan, and timing chain cover to keep the price down. To top it off, he bought a new oil pump from PAW and bolted the short-block together.
Vortec Head Mods
Before Tim could bolt the Vortec heads on the engine, the castings required a slight tweaking to accommodate the larger HOT cam. The stock Vortec valvesprings cannot handle the HOT cam’s 0.525-inch lift using the 1.6 roller rockers, so the tops of the valve guides must be machined shorter to clear the retainer. The spring pockets must also be opened up for the slightly larger-diameter springs. Tim also had the heads machined for ARP screw-in studs, but he did not use guideplates because he was using rail-style rocker arms.
The machine work for the springs configures the heads for the LT4 valvesprings that can handle the 0.525-inch lift and are also durability tested by Chevrolet to withstand performance abuse for hours on end. In fact, these heads and springs have individually been tested with Chevy’s 300-hour wide-open throttle durability test and passed without failure. That’s how good these components are.
Because the Vortec heads use a 64cc chamber, Tim used a Federal-Mogul hypereutectic 10cc dished piston to keep the compression ratio in line. Even with the 0.005-inch deck height and the Fel-Pro composition head gasket, the compression is still streetable at 9.6:1. That’s at the high end of a streetable compression ratio with iron cylinder heads, but combined with this camshaft should make excellent torque and not suffer from detonation.
Conclusion
Because of time constraints, we were not able to dyno-test this combination, but we will follow up with a test as soon as we can bolt the motor on the test stand. According to informed sources and our previous experience with the Vortec heads, this combination should make between 400 and 415 hp at 6,000 rpm, and around 420 lb-ft of torque at 4,000 rpm. These are excellent power numbers, especially when you consider that the long-block could be constructed for under $2,500. Taken as a whole, this is a great engine combination at an incredibly inexpensive price.
Hot, Hot, Hot, Part II
422 HP From A Budget Vortec Head/HOT Cam 355ci Mouse
By Jeff Smith
Some things are difficult to improve. It’s tough to come up with an improvement on the wheel, and when it comes to small-block Chevy engines, it used to require considerable skill to make 400 hp with stock iron heads and a streetable cam—and all this on a budget. Now we’ll show you how anybody can do it.
In the previous story we introduced you to budget-buildup artist Tim Moore’s 355ci small-block featuring its stock Vortec iron heads, GM Performance Parts HOT cam, and 9.75:1 compression ratio. By rebuilding a one-piece rear-main seal, hydraulic roller cam small-block using cast pistons and a stack of high-perf GM Performance Parts goodies, we estimated over 400 hp. The best part is that we did all this for under $2,500.
But going in, we only guessed how much power this engine was going to crank out. So we trucked this iron-headed small-block out to Westech Performance and let John Baechtel and Steve Brulé abuse this Mouse on their SuperFlow dyno. Moore elected to use an old Stinger electronic ignition distributor to trigger the MSD 6 box used on Westech’s dyno. This also required a special melonized GM distributor gear to ensure the gear would live when used with the GM Performance Parts HOT hydraulic roller camshaft. This gear is not cheap, but it does work. As for exhaust, we bolted on a set of Hooker 15/8-inch headers along with a 2½-inch exhaust system plumbed to a pair of Flowmaster mufflers. For the final piece of the puzzle, we added a Barry Grant Speed Demon 750 mechanical-secondary carburetor to ensure that the carburetor would not restrict power.
Test Time
Since this was a newly rebuilt engine, we pre-oiled the assembly and set the static timing to allow it to fire up immediately. Moore set the total timing at 34 degrees and then allowed the engine a short 20-minute break-in session. Finally, with a nice leak-free engine, we loaded up the fuel cell with 92-octane 76 gasoline and pulled the handle.
For this initial test, we used the GM Performance Parts dual-plane Vortec intake manifold. The first thing we wanted to see was how well the engine idled. The motor responded with an amazing 14 inches of manifold vacuum at 850 rpm, which means this could easily support vacuum-operated accessories like power brakes. The first few pulls looked slightly rich, so Brulé pulled two jet sizes out of the carb, but first we had to do a minor tune-up on the driver-side header.
One reason the Vortec heads work so well is because of the superior chamber design and the fact that the engineers moved the spark plug closer to the exhaust side of the chamber. Vortec heads are a straight-plug design that sometimes can cause header clearance problems. In the case of the Hooker headers, the No. 5 spark-plug boot was pushed too close to the header tube and melted. This required us to heat and dent the header to create enough air gap to protect the spark plug–wire boot.
Once we had all eight cylinders firing with slightly leaner jets in the Demon carburetor, the 355 pulled up some impressive numbers. Even at 2,500 rpm, the 350 managed 359 lb-ft of torque with a max torque of 423 lb-ft at 4,400. Peak horsepower came in at 412 at 5,600 rpm, creating a somewhat narrow powerband of only 1,200 rpm, but looking more closely at the numbers reveals the engine is punching out 400 lb-ft from 3,500 all the way through 5,300 rpm.
While these numbers are respectable, we also wanted to try the Edelbrock Super Victor single-plane intake for Vortec heads. We expected the single plane would trade power below peak torque for more power above peak torque. Generally, this is not a good trade for street engines, but Moore also plans to use nitrous on this engine and felt that the single-plane intake would work better with a plate nitrous system.
Changing intakes was a snap, and once again we were working this small-block. After a few minor tweaks, the numbers looked very good, but we also decided to try adding a 1-inch spacer as well as an additional ½-inch spacer to simulate the nitrous plate. We also experimented with reducing the timing to 32 degrees total instead of the previous test’s 34 degrees.
Not surprisingly, the 355 did sacrifice some power down low, but actually very little. What was more surprising was the 422 hp (a 10hp gain) at 5,700 rpm we saw over the dual plane. The trade-off was torque, where the single-plane intake managed to still muster 418 lb-ft of torque at 5,000. The peak horsepower rpm points were almost identical, yet the single plane managed 10 more horsepower and created a virtually identical average torque figure.
Conclusion
What this all comes down to is a great small-block. The dual plane made at least 360 lb-ft of torque from 2,500 to 6,000 rpm, and the single plane was only slightly behind. But the single-plane version cranks up the horsepower with well over 420 ponies.
We didn’t try this, but with only 32 degrees of total timing, it’s entirely possible that despite its 9.75:1 compression ratio, this engine might run just as hard on 87-octane gas as it did on 92-octane gas. This is a direct result of a tight quench area, an excellent combustion-chamber design, and careful attention to assembly. Add the 150-175hp nitrous system that Moore wants to run and we’re talking about a thumper 11-second street car. Even with a Demon carb, headers, an ignition, and a nitrous kit, you still could build this complete engine setup for under $4,000, and that’s if you bought everything new. That’s a winning combination any way you look at it.
An Inexpensive Roller Cam 400hp Small-Block
By Jeff Smith
photographer: Jeff Smith
Face it: Everybody’s looking for The Deal—you know, the 400hp motor for $100. We’re not there yet, but we’re always searching for better ways to build a small-block and we think we’ve stumbled onto one that is plenty hot. The key to a strong engine is the combination of great heads and an excellent camshaft. Improved airflow is usually accompanied by a hefty price tag, but check out this combo: Start with a late-model roller cam 350ci block. Bolt on a set of Vortec iron heads and a GM Performance Parts HOT hydraulic roller cam. Sprinkle on an aluminum GM Vortec dual-plane intake and you have an outstanding combination of all-new parts, with the heads, cam, and intake costing less than $800!
Our pal Tim Moore is building this exact package. But before you dive right into this deal, there are a few important details that you need to know that could save you money. The hinge pin to this plan is an ’88-or-later 350ci roller-cam cylinder block. Chevy put these engines in Camaros, Firebirds, police cars, some Caprices, and ¾-ton truck chassis also used in motor homes. These roller cam blocks differ from earlier blocks in several significant ways.
Block Tech
Starting in ’87, Chevy converted all small-blocks to a one-piece rear-main seal combined with an excellent one-piece oil pan seal. Chevy followed that in ’88 with hydraulic roller cams in most V-8 engines. To accommodate the taller hydraulic roller lifter, Chevy increased the height of the lifter boss. This also required two small cast-in bosses in the middle of the lifter valley to mount the sheetmetal retainer, called the “spider,” which retains each pair of lifters.
All this block information is given for several reasons. The GM Performance Parts HOT hydraulic roller is a great, affordable cam ($175 from Scoggin-Dickey Performance) and begs to be matched with a set of Vortec heads. This OEM-style roller cam is intended to work in ’88-and-later roller cam small-blocks, because it requires a production thrust plate. However, according to our erudite engine enthusiast Kevin McClelland, you can use this cam in an early two-piece rear-main seal block. Trim the ears off the production roller-cam thrust plate and use it as a spacer between the cam gear and the block. Then employ a thrust button to control cam endplay. This will require using aftermarket hydraulic roller tappets, which are more expensive than the factory hydraulic roller tappets. This way, you could use your existing, older two-piece rear-main seal block.
Since Tim was building a whole new motor, he latched onto a used roller cam 350ci short-block that came out of an ’89 Caprice police car. He disassembled it, had the crank machined and the rods rebuilt, and added a set of Federal-Mogul hypereutectic pistons. He also measured the deck height and had the block milled to establish a 0.005-inch piston-to-deck clearance. He also used the inexpensive GM Performance Parts cam drive assembly for the roller cam that is a screamin’ deal at $40. Tim re-used the stock hydraulic lifters, oil pan, and timing chain cover to keep the price down. To top it off, he bought a new oil pump from PAW and bolted the short-block together.
Vortec Head Mods
Before Tim could bolt the Vortec heads on the engine, the castings required a slight tweaking to accommodate the larger HOT cam. The stock Vortec valvesprings cannot handle the HOT cam’s 0.525-inch lift using the 1.6 roller rockers, so the tops of the valve guides must be machined shorter to clear the retainer. The spring pockets must also be opened up for the slightly larger-diameter springs. Tim also had the heads machined for ARP screw-in studs, but he did not use guideplates because he was using rail-style rocker arms.
The machine work for the springs configures the heads for the LT4 valvesprings that can handle the 0.525-inch lift and are also durability tested by Chevrolet to withstand performance abuse for hours on end. In fact, these heads and springs have individually been tested with Chevy’s 300-hour wide-open throttle durability test and passed without failure. That’s how good these components are.
Because the Vortec heads use a 64cc chamber, Tim used a Federal-Mogul hypereutectic 10cc dished piston to keep the compression ratio in line. Even with the 0.005-inch deck height and the Fel-Pro composition head gasket, the compression is still streetable at 9.6:1. That’s at the high end of a streetable compression ratio with iron cylinder heads, but combined with this camshaft should make excellent torque and not suffer from detonation.
Conclusion
Because of time constraints, we were not able to dyno-test this combination, but we will follow up with a test as soon as we can bolt the motor on the test stand. According to informed sources and our previous experience with the Vortec heads, this combination should make between 400 and 415 hp at 6,000 rpm, and around 420 lb-ft of torque at 4,000 rpm. These are excellent power numbers, especially when you consider that the long-block could be constructed for under $2,500. Taken as a whole, this is a great engine combination at an incredibly inexpensive price.
Hot, Hot, Hot, Part II
422 HP From A Budget Vortec Head/HOT Cam 355ci Mouse
By Jeff Smith
Some things are difficult to improve. It’s tough to come up with an improvement on the wheel, and when it comes to small-block Chevy engines, it used to require considerable skill to make 400 hp with stock iron heads and a streetable cam—and all this on a budget. Now we’ll show you how anybody can do it.
In the previous story we introduced you to budget-buildup artist Tim Moore’s 355ci small-block featuring its stock Vortec iron heads, GM Performance Parts HOT cam, and 9.75:1 compression ratio. By rebuilding a one-piece rear-main seal, hydraulic roller cam small-block using cast pistons and a stack of high-perf GM Performance Parts goodies, we estimated over 400 hp. The best part is that we did all this for under $2,500.
But going in, we only guessed how much power this engine was going to crank out. So we trucked this iron-headed small-block out to Westech Performance and let John Baechtel and Steve Brulé abuse this Mouse on their SuperFlow dyno. Moore elected to use an old Stinger electronic ignition distributor to trigger the MSD 6 box used on Westech’s dyno. This also required a special melonized GM distributor gear to ensure the gear would live when used with the GM Performance Parts HOT hydraulic roller camshaft. This gear is not cheap, but it does work. As for exhaust, we bolted on a set of Hooker 15/8-inch headers along with a 2½-inch exhaust system plumbed to a pair of Flowmaster mufflers. For the final piece of the puzzle, we added a Barry Grant Speed Demon 750 mechanical-secondary carburetor to ensure that the carburetor would not restrict power.
Test Time
Since this was a newly rebuilt engine, we pre-oiled the assembly and set the static timing to allow it to fire up immediately. Moore set the total timing at 34 degrees and then allowed the engine a short 20-minute break-in session. Finally, with a nice leak-free engine, we loaded up the fuel cell with 92-octane 76 gasoline and pulled the handle.
For this initial test, we used the GM Performance Parts dual-plane Vortec intake manifold. The first thing we wanted to see was how well the engine idled. The motor responded with an amazing 14 inches of manifold vacuum at 850 rpm, which means this could easily support vacuum-operated accessories like power brakes. The first few pulls looked slightly rich, so Brulé pulled two jet sizes out of the carb, but first we had to do a minor tune-up on the driver-side header.
One reason the Vortec heads work so well is because of the superior chamber design and the fact that the engineers moved the spark plug closer to the exhaust side of the chamber. Vortec heads are a straight-plug design that sometimes can cause header clearance problems. In the case of the Hooker headers, the No. 5 spark-plug boot was pushed too close to the header tube and melted. This required us to heat and dent the header to create enough air gap to protect the spark plug–wire boot.
Once we had all eight cylinders firing with slightly leaner jets in the Demon carburetor, the 355 pulled up some impressive numbers. Even at 2,500 rpm, the 350 managed 359 lb-ft of torque with a max torque of 423 lb-ft at 4,400. Peak horsepower came in at 412 at 5,600 rpm, creating a somewhat narrow powerband of only 1,200 rpm, but looking more closely at the numbers reveals the engine is punching out 400 lb-ft from 3,500 all the way through 5,300 rpm.
While these numbers are respectable, we also wanted to try the Edelbrock Super Victor single-plane intake for Vortec heads. We expected the single plane would trade power below peak torque for more power above peak torque. Generally, this is not a good trade for street engines, but Moore also plans to use nitrous on this engine and felt that the single-plane intake would work better with a plate nitrous system.
Changing intakes was a snap, and once again we were working this small-block. After a few minor tweaks, the numbers looked very good, but we also decided to try adding a 1-inch spacer as well as an additional ½-inch spacer to simulate the nitrous plate. We also experimented with reducing the timing to 32 degrees total instead of the previous test’s 34 degrees.
Not surprisingly, the 355 did sacrifice some power down low, but actually very little. What was more surprising was the 422 hp (a 10hp gain) at 5,700 rpm we saw over the dual plane. The trade-off was torque, where the single-plane intake managed to still muster 418 lb-ft of torque at 5,000. The peak horsepower rpm points were almost identical, yet the single plane managed 10 more horsepower and created a virtually identical average torque figure.
Conclusion
What this all comes down to is a great small-block. The dual plane made at least 360 lb-ft of torque from 2,500 to 6,000 rpm, and the single plane was only slightly behind. But the single-plane version cranks up the horsepower with well over 420 ponies.
We didn’t try this, but with only 32 degrees of total timing, it’s entirely possible that despite its 9.75:1 compression ratio, this engine might run just as hard on 87-octane gas as it did on 92-octane gas. This is a direct result of a tight quench area, an excellent combustion-chamber design, and careful attention to assembly. Add the 150-175hp nitrous system that Moore wants to run and we’re talking about a thumper 11-second street car. Even with a Demon carb, headers, an ignition, and a nitrous kit, you still could build this complete engine setup for under $4,000, and that’s if you bought everything new. That’s a winning combination any way you look at it.
08-13-2008, 06:28 PM
#2
Team Owner
Member Since: Aug 2006
Location: Columbia Missouri
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Wow, that's impressive. I can't wait until Curt and I can dyno his new 355 in his Vette. Surprisingly, it's very similar to that build. Vortec block, 9.75:1 CR, after market Vortec heads, very aggressive marine roller cam, dual plane intake, headers...it FEELS like a 400 HP motor...but we won't know until it dynos.
That was good reading, thanks.
That was good reading, thanks.
08-13-2008, 09:26 PM
#5
Race Director
it made very-similar numbers (400-HP/400-TQ? ), had better-flowing heads for future build-ups, and cost approx $3600-complete (I lost that particular issue, and am going straight from memory)
08-14-2008, 02:34 AM
#6
Drifting
Jeff Smith knows his stuff.
I'm going up with some friends to his house to watch his son play in his first college football game on the 30th, if I remember i'll see if I can get him to stop by and add any more information to this thread.
I'm going up with some friends to his house to watch his son play in his first college football game on the 30th, if I remember i'll see if I can get him to stop by and add any more information to this thread.
08-14-2008, 11:07 AM
#8
Melting Slicks
08-14-2008, 02:07 PM
#9
Le Mans Master
The Vortec blocks are becoming the commodity that the GEN I flat-tappet blocks were 20 years ago. Plentiful and cheap, with roller cams (you can reuse the lifters), Vortec head that outflow the aftermarket S/R heads and little or no bore wear.
Vortecs and cheap factory roller cams have completely changed the SBC universe - I built my last flat-tappet engine a while ago and I won't build another one.
It's raining soup - grab a bucket
Vortecs and cheap factory roller cams have completely changed the SBC universe - I built my last flat-tappet engine a while ago and I won't build another one.
It's raining soup - grab a bucket
Last edited by billla; 08-14-2008 at 02:10 PM.
08-15-2008, 02:37 PM
#10
Le Mans Master
After reading that build up above.....its basically a Year One crate motor now days.....They spent $2500 on building it.....You can get a Y1 motor for $3k with no core needed or anything.....Definetly seems like the best bang for the buck if all you want is 400hp or less.
I wish more people were posting up if they have dynoed the Y1 motors in their cars and see what kind of RWHP they are pulling... I would guess around 300rwhp in a manual car with all accessories and IRS. Still enough for low 13s though.......Not bad for $3k
I wish more people were posting up if they have dynoed the Y1 motors in their cars and see what kind of RWHP they are pulling... I would guess around 300rwhp in a manual car with all accessories and IRS. Still enough for low 13s though.......Not bad for $3k
08-15-2008, 04:10 PM
#11
Burning Brakes
I posted this in another spot earlier. It is a build up I did this winter and just got the final numbers. I think I spent about 1500 bucks for the parts:
My 1980 L48 just came from the dyno and produced 300 RWH. 355 TQ. Now if you add 15% for drive line loss she looks pretty good. I have cast vortec heads, flat top pistons, 30 over on the bore, 480 lift crane cam, msd box and coil, Dyno Max coated headders, it is fun!
My 1980 L48 just came from the dyno and produced 300 RWH. 355 TQ. Now if you add 15% for drive line loss she looks pretty good. I have cast vortec heads, flat top pistons, 30 over on the bore, 480 lift crane cam, msd box and coil, Dyno Max coated headders, it is fun!
08-15-2008, 04:46 PM
#12
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WOW, I'm glad to see that someone will use thie thread for something ! Enjoy guys, say does anyone know what magazine article (CHP, POPHOTROD, COR, ect) it was a recent issue about intake shootout, which was the best intake for this combo?
08-15-2008, 05:27 PM
#13
Drifting
08-15-2008, 08:25 PM
#14
Race Director
After reading that build up above.....its basically a Year One crate motor now days.....They spent $2500 on building it.....You can get a Y1 motor for $3k with no core needed or anything.....Definetly seems like the best bang for the buck if all you want is 400hp or less.
I wish more people were posting up if they have dynoed the Y1 motors in their cars and see what kind of RWHP they are pulling... I would guess around 300rwhp in a manual car with all accessories and IRS. Still enough for low 13s though.......Not bad for $3k
I wish more people were posting up if they have dynoed the Y1 motors in their cars and see what kind of RWHP they are pulling... I would guess around 300rwhp in a manual car with all accessories and IRS. Still enough for low 13s though.......Not bad for $3k
That's right, put it on an chassis dyno if it makes 300+RWHP it is very close to being a 400HP motor as far as I'm concerned.
Problem is, it is not easy to make that HP at the rear wheels with a 355ci motor as many have found out, including myself.
08-15-2008, 09:07 PM
#15
Le Mans Master
I've torn into a couple of Vortec engines now - they usually have virtually no bore wear and they're often good for just a "bottle brush" hone, re-ring, bearings and go. We're not talking about a "bubba" rebuild here...they're just within service limits unlike most of the GEN I junk you find these days that are on their 2nd or 3rd rebuild.
It's really not that hard to hit the high 300's with one of these engines with the right cam - the factory roller really changes the reasonable power targets for a performance rebuild and the cost.
It's really not that hard to hit the high 300's with one of these engines with the right cam - the factory roller really changes the reasonable power targets for a performance rebuild and the cost.
08-15-2008, 09:49 PM
#16
Pro
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That particular article was the inspiration for my engine. The only difference would be the XR-270 comp cam and Z06 behive valve spring (that are direct fit with no mod). I have a Super Victor single plane under a Q-jet (It had to be fitted). I love that combination. Really streetable with a nice 21 MPG.
I have the video in my sig of my rwhp at 314 with the dual plane intake. I plan on doing one with the single plane this summer.
Stephan
