I think you correct, it will not be a race car. So if I got close 450 HK that will be fine.
I would appreciate advice on a good cam.
Building a 340 engine
- Thread starter Magnus707
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I think you correct, it will not be a race car. So if I got close 450 HK that will be fine.
I would appreciate advice on a good cam.
Thanks for you replay! The original weight is 2,773lbs. I think it will be about the same when I have swap the Engine, transmission,
and rear axle.
AKI is what you're calling PON. It's exactly what I posted. I wouldn't call it 'almost the same' unless you actually know the PON for EU. The Motor Octane number can vary quite a bit.
B3422w5
Well-Known Member
You are correct, I might make it to simple.
nm9stheham
Well-Known Member
As noted, European 98 Octane is about the same as US 93 octane. So we can work with that for now.
OP, with the heads you have, then you should be expecting between 350 and 400 HP.... which is the 1 to 1.1 HP per cubic inch mentioned by 273. The heads as they sit without modifications simply do not provide the flow for more HP. So I will assume you are OK with that; with a 3.73 rear gear and the lighter weight that you say, it will be very fun to drive.
For your daily driver, then the operation is going to need a wider torque curve than a race-only engine and I suspect you will not want to use a LOT of fuel. So that is indicating a pretty standard, mild performance cam. Probably a cam that is 10 degree more duration than what you now have. You can go more than that but then fuel consumption goes up and up. If you get a cam with higher lift and limited duration, then you are going to be about optimum for the street use.
Looking at a few cams, I like the Howard's 711451-08, which is optimized for the larger Mopar lifter diameter. 265 advertised duration, 220 duration at .050", 108 LSA, and 104 ICL. But the good thing about that am is that the lift rating at a 1.5 rocker ratio (like you have) is .506". That is about as good as you can do for a catalog, hydraulic flat tappet lifter cam.
So running with that type of cam advertised duration, we can finally look at pistons. The goal would be to that will work with that type of cam to produce a dynamic compression ratio (DCR) of around 8.0 at sea level there in Stockholm.
The KB107 flat top works out to a 8.6-8.7 DCR with the above cam, and that is higher than most of us can successfully run on pump fuel without detonation. If we switch to the Icon IC742, then the DCR drops down to 8.0 to 8.2 with a cam like that above. As long as you keep the DCR to around 8 or more, then the low RPM torque is going to be more than you can connect through the tires.
If you wanted more peak power, then a larger cam like the Howard's listed above would be suitable, and then the KB107's might work.
OP, with the heads you have, then you should be expecting between 350 and 400 HP.... which is the 1 to 1.1 HP per cubic inch mentioned by 273. The heads as they sit without modifications simply do not provide the flow for more HP. So I will assume you are OK with that; with a 3.73 rear gear and the lighter weight that you say, it will be very fun to drive.
For your daily driver, then the operation is going to need a wider torque curve than a race-only engine and I suspect you will not want to use a LOT of fuel. So that is indicating a pretty standard, mild performance cam. Probably a cam that is 10 degree more duration than what you now have. You can go more than that but then fuel consumption goes up and up. If you get a cam with higher lift and limited duration, then you are going to be about optimum for the street use.
Looking at a few cams, I like the Howard's 711451-08, which is optimized for the larger Mopar lifter diameter. 265 advertised duration, 220 duration at .050", 108 LSA, and 104 ICL. But the good thing about that am is that the lift rating at a 1.5 rocker ratio (like you have) is .506". That is about as good as you can do for a catalog, hydraulic flat tappet lifter cam.
So running with that type of cam advertised duration, we can finally look at pistons. The goal would be to that will work with that type of cam to produce a dynamic compression ratio (DCR) of around 8.0 at sea level there in Stockholm.
The KB107 flat top works out to a 8.6-8.7 DCR with the above cam, and that is higher than most of us can successfully run on pump fuel without detonation. If we switch to the Icon IC742, then the DCR drops down to 8.0 to 8.2 with a cam like that above. As long as you keep the DCR to around 8 or more, then the low RPM torque is going to be more than you can connect through the tires.
If you wanted more peak power, then a larger cam like the Howard's listed above would be suitable, and then the KB107's might work.
Exactly what He just said. As close to perfect as you can get for what your wanting to put together.
Wyrmrider
Well-Known Member
I like the howards or a Lunati Voodoo also
but he owns a cam that is slightly larger than the 340 HP cam at .050
slightly shorter exhaust, but that's good a as he has headers
so
IMHO not worth spending money on a cam change unless he could do a swap/ exchange
I do not like comp but he has what he has and it will work with the rest of his parts and heavy vehicle
cheers
but he owns a cam that is slightly larger than the 340 HP cam at .050
slightly shorter exhaust, but that's good a as he has headers
so
IMHO not worth spending money on a cam change unless he could do a swap/ exchange
I do not like comp but he has what he has and it will work with the rest of his parts and heavy vehicle
cheers
1st ones is a 5.9l 380hp create engine 2nd is a 300 hp create engine aka stock 5.9l and Mod is with Eddie heads and a 275 roller cam swap if I remember right.
On the street most times your gonna be giving it from 0-20 mph to about 50 mph, so 1st and a bit of 2nd. 1st at 50 mph is about 5500 rpm with your gearing.
If you look at 4000 rpm, 36 mph in 1st, the stock and eddie head engine are making the same power and stock is making more below. Above 5000 rpm hp is gonna have little effect on the street, especially if you kill bottom end under 4000 rpm to get it.
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Ahhhhhh yes! Now that completes your post!
NOT a fan of the lower grade unit.
Thanks for the link! It’s worth the read.
nm9stheham
Well-Known Member
Porting or other heads to get more head flow. That is why so many good folks here spend so much time talking about head flow.... it is the one key limit that you have to eventually get past to get to more HP. A big cam will not make the heads flow more than they can flow.
But your emphasis on peak HP does not match up exactly with what I thought you wanted to do with the engine and car; I think you said 'almost a daily driver'. (But I may be interpreting that wrong, and it may be the translation of language.)
But your emphasis on peak HP does not match up exactly with what I thought you wanted to do with the engine and car; I think you said 'almost a daily driver'. (But I may be interpreting that wrong, and it may be the translation of language.)
- What are the maximum speeds at which you intend to drive?
- Will you use this on the drag strip?
- Do you like straight line power, like on a drag strip, or the ability to use the engine torque in corners like in a rally or road race car?
- How important is fuel mileage to you?
Air flow "cfm" basically is power , engine size is at what rpm that power is made Eg. 450hp 371cid 2500-6000 rpm vs 450hp 410cid 1800-5300 rpm. So top end cam, heads, bores size, cr, carb, etc.. = hp, Bottom end, displacement = powerband rpm.
Heads more than anything determine HP capability, cam and intake and exhaust track is just gonna determine what % of that air flow is gonna be used.
The rule of thumb is 2hp per head cfm, but with street cam and cr it's more like 1.9 for 10:1cr 285 cam, 1.8 for like 9:1cr 270 cam etc..
If it were “I” building this engine with what you listed, I would just simply fully port the Edelbrock heads with the stock valve sizes, use the RPM intake, a 750 carb, throw the cam away for one with 20* more duration.
(I’d look at Lunati solid flat tappet cams....)
The short block would be forged zero deck pistons with deep valve reliefs. Depending on the cams lift, perhaps a rocker ratio upgrade.
(I’d look at Lunati solid flat tappet cams....)
The short block would be forged zero deck pistons with deep valve reliefs. Depending on the cams lift, perhaps a rocker ratio upgrade.
Wyrmrider
Well-Known Member
When picking heads pick your rev range first
that will determine cam lift
then get heads that maximise the lift you are going to have
getting heads that flow big time at high lifts frequently give up flow in the lifts a street build can use
rocker ratio helps but roller rockers + B3 kit gets pricey and 1.65 can be done but also pricey
Magnum heads can go 1.7 but 1.6 is free
that will determine cam lift
then get heads that maximise the lift you are going to have
getting heads that flow big time at high lifts frequently give up flow in the lifts a street build can use
rocker ratio helps but roller rockers + B3 kit gets pricey and 1.65 can be done but also pricey
Magnum heads can go 1.7 but 1.6 is free
Frequently? I guess you have seen a bunch of crappy work done then. LMAO!
If the head is ported correctly, there is no low end lift loss. Porting his heads for his application Ian a full crazy gutting cut the head in half to re-weld it.
If the head is ported correctly, there is no low end lift loss. Porting his heads for his application Ian a full crazy gutting cut the head in half to re-weld it.
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