v2racing

Exactly! Like I said. It would be perfect for my cruiser. It only has a 260 Merc (350 Chev). It could use a little more oomph. It's not my idea of what a high performance Corvette engine is.

63mako

I like high RPM too. My Vette had a 302 in it when I got it. I raced for years and blew up a lot of engines some @ 8000 RPM. That said it cost a lot more now to build a 7500 RPM engine. When you get to 434 CI and 550-600 Hp it gets really expensive. RPM kills engines, that is a fact. With a 4" stroke the SBC platform has limited space and sizes for every part yet have to handle over twice the loading and with a 4" stroke and 7500 RPM piston speeds are off the chart for the size of the parts compared to big blocks. It is great in a street car to lower the powerband and have the torque where you run 95% of the time, even if you give up some peak HP to do it. That cam has slower ramps than some, less lift than some and a lower operating range than some. It will still run to 6000 RPM shifts and way more likely to stay together long term. Nice street engine or boat engine, not the best pure 1/4 mile build but with the upgrades it will smoke almost anything on the street and with the automatic, don't need huge drivetrain upgrades to stay together. There are thousands of ways to approach any build but the key is give the poster the direction to achieve HIS goals.

garygnu

look at a 4/7 swap solid roller cam from comp .part number 12-823-14 [14] ,47s 288r-6 .how built is the drive train ?maybe try a good desk top dyno set up to see what cam will make what power .a corvette is made with fiber glass ,like most boats .

c3_dk

That is a very good way of telling how we think here in Denmark.
Thanks 63mako

c3_dk

Also thanks for this 63mako. It is long way to USA from Denmark, and sometimes we need some help

63mako

I know it is a long way. My Great Grandfather Peter Jensen made the trip from Denmark on a boat in 1915. Always wanted to go there.

v2racing

I agree! My 406 will spin to 7500 and still make power. It doesn't mean I drive it that way. I'd be in trouble all the time and wouldn't have a drivers license. It still makes plenty of bottom end torque, but with a 3500 rpm converter, the bottom end isn't just off idle.

Back many years ago before anyone made engine cases or cylinders that would take huge bores in the Harleys, the only way we could get big cubic inches was with stroke. The biggest bore the cases would take was 3 13/16" so we would run 5" stroke in the gas engines to get 114 CI. We spun our Prostock engine to 7500 rpm and sometimes our rider would accidentally spin it to 8000 with that 5" stroke. The wrist pins were a lot smaller on that than a SBC. I always made the pistons as light as I possibly could. Did a lot of machining on them. Nowadays they have cases that will take 5" bore.

My Top Fuel Bike I rode had a 5 1/4" stroke. It would go through the traps at 7000 RPM @ 199 and change MPH. That was World Record MPH at the time. I sold the bike at about that time and retired from riding. The MPH record held for several years though.

MotorHead

Get the proper heads for the engine, 180cc on a 434ci engine is insane

c3_dk

Please come, we are a small but beautiful country.
And then you also can spend a few hours working on my car :- )

Peter Jensen is a very common name here in Denmark, back in the old days, Jensen meant "Jens had a son, his name will then be Jensen, or in English Jenson

Also this means that your are a bit Danish :- )

c3_dk

Hi,

Can you tell me a bit about your engine?
What parts have you bought ec ec.

Th,
John

63mako

That is correct Mr. Motorhead.

Little Mouse

Wish I had control of Harley. The sportster would no longer be the joke it is on performance. New engine around 48 spread on the cylinders so the look would not change much more room for big over square cylinders and fuel injectors for each cylinder, lighter flywheel. 6 speed close ratio trans with lower 1 rst gear to help lower flywheel weight, trans now close ratio for less rpm drops between shifts. shift pattern 1 up five down. Weight comes down on the fat pig weight and all the chopper imitation garbage gone . 18 inch rims front and back a more XLCH bike for todays times. Sportster coolest name in motorcycling all Harley does with it use it as a **** poor chopper imitation.

A person has to laugh when you see someone get on there Harley, real slow reving acceleration tractor crap engine, belongs on a farm somewhere.

bluedawg

What size engine is in your 48? I want to do heads cam and big bore kit on my dyna, but I feel the way you do about the power. My twin cam 96" comes with around 70 rwhp stock and imho that's weak, with the above mentioned mods I can get it up to 120 rwhp with the 2 into 1 header and the programmer. My wife's sportster seems a little quicker off the line but with the 1200r the power to weight is better.

v2racing

It is a .030" over 400 block with billet 4 bolt splayed main caps. The crank is a 4340 forged Scat with the Scat Pro Comp I beam rods with ARP 7/16" cap screws. These are nice rods for the money. The pistons are Ross Ultralight forged flat tops. I balanced all the parts to less than 1/4 gram from each other then matched the the lighter pistons with rods that were heavier at the small end. The result was almost zero difference from cylinder to cylinder.

The heads are Brodix -10 that have 2.100" and 1.600" valves in 64cc chambers. I did a lot of work in them and they flow way over 300 CFM on a Superflow 600 bench @ 28" of water. The low and mid lift flows are very good also. I concentrate on low and mid lift flow on the exhaust side because this is where the pressures are highest and most of the exhaust is evacuated and these do well there. If you have to push exhaust out with the piston at the high lifts, you have a pumping loss and that means HP loss. I matched the chambers to the cylinder bore and relieved around the valves with a special radius cutter I had Sunnen make. The seat shapes are designs I developed over the years and I also have custom made cutters for these. I have special back angle, back cuts and seat and back cut widths that work with my seat shapes. This is what allows me to make very healthy high lift flows and still make high low and mid lift flows.

The compression is 11.85 to 1 with a tight .034" quench (squish).

The intake is a Victor Jr. that is heavily modified. I had to weld on the manifold to make the runners big enough to match the heads. I would have gone for a bigger manifold and make things easier, but it needed to fit under my 80 Vette's stock hood. On the 75 I have an L88 hood with an air chamber I glassed in and it gives me another 1 1/2" to put spacers under the carb. I am putting a 1" HVH (HVC) type spacer with a phenolic 1/2" open spacer under that with it all blended into the upper end of the plenum and on into the runners.

I have several carbs, but the one that I use most is an old Barry Grant built 750 DP. It was done before he started Demon Carbs. I have done more modding and a lot of tuning to it. I got great mileage, throttle response and power, a lot of power!

The cams is a custom grind I had done that is fairly short at advertised duration, but fairly wide by .200" lobe lift. It gives me a nice broad power-band like this. I run the lash very tight on this cam and this engine loves it. .010" intake and .012" exhaust hot. Through the 3" X pipe exhaust, it sounds big and pretty mean. People were always asking if it was a big block.

It is a nasty little 406. The 406 that came out of my 75 when I got it was dynoed at 545 horse and 530 torque. This 406 would run circles around that one. The rest is in my signature.

Little Mouse

no not the 48 Harley sportster. I ment move the spread on the cylinders from 45 to 48 degrees to help with way bigger cylinder bores more room for individual fuel injection, make the head where one fuel injector comes off the front head goes out on the left side of the bike the rear head have it come off the right side. total BS one injector doing two cylinders or one carb in the past. but im pretty sure Harley won't let me run the company. Two professional drag racers tested a bunch of bikes. just a simple 865cc triumph bonneville was a half second quicker in the quarter mile then a 1200 cc harley 48. I know they have the v-rod as there performance bike but the sportster does not have to be a total slug

bluedawg

I agree that it don't have slug.

MotorHead

Thankyou, you may continue to give advice.

v2racing

It's not too hard to make 105 to 110 RWHP out of a stock CC 1200 Sporster with off the shelf parts and good head work. Granted it's not the HP to weight ratio of the import sport bikes, but with a "Y" intake push rod V-Twin it's not bad. Remember it's not that far from the 1957 design, so near 1.5 horse per cube at the rear wheel and reliable daily rider is OK.

PS: I've seen it said here that motorcycles don't have much loss from the engine to the rear wheel. Not so. When Buell had the 101 horse
(at crank) motor, they only made about 74 at the rear wheel. The primary drive drags a triple row chain through an oil bath, not to mention a clutch drum and an alternator rotor.

c3_dk

Sweet engine you have.
But when you have almost 12:1 doesn't that mean very high octane gas?
My L46 11:1 run on Shell 99 octane and still I can hear "knocking"
(99 octane in Europe is 93-94 octane in USA I think)

Thx,
John

bluedawg

I love my Harley as under powered as it is. Love my corvette more, and when I've got my vette pretty much the way I want it, I'll build my 96" up to a 106". If you look at the v twin its basically a tractor engine, not as bad as a uerl. There are much faster bikes, even American made, but there not the bike I'd want. My brother owns a vrod and if I were to buy another bike that would probably be the one.