pillowmeto

I'm planning to put together a killer juiced 355 this summer making loads of power. Problem is it will have iron heads on it and i expect it to run very hot.
Are there any tricks out there to keep the heads cool. Maybe something to paint them with that helps in heat dissipation or can a gen 1 SBCs run a reverse coolant flow to cool the heads first?
So far i plan to pull the radiator from a 86 vette in a junkyard and use it's electric fans as well :yesnod:

thanks in advance

MAtt

duntovlives

this may sound dumb....but, why do you expect it to run hot?

pillowmeto

I expect it to run hot because I'm pushing for 500 hp with a 355.
It will run ~10:1 compression on pump gas. And while this may not make it technically be quite hot, the compression is up there for an iron headed pump gas engine
general rule of thumb is 9.5:1 for iron heads and 10.5:1 for aluminum because more heat is dissipated through the aluminum.
So if i can lower the temperature of the heads or allow them to dissipate more head, it could run a higher compression ratio, which means more power. If i were to run 10.5:1 with that setup on 93 octane, i would expect it to detonate.
basically the cooler i can get my heads, the more power i can have, but my main point of interest is that i plan to run 10:1 compression and id like to not have to drop to 9.5:1, so cooling the heads a bit more than normal could then just give me more peace of mind against knock.
This is also going to be a nitrous motor so after a fast run with it it might heat up enough that it could detonate fairly easily. Thats mostly where it would come in to play, the faster heat dissipation that is.

Wow that answer turned out longer than i expected.

MAtt

duntovlives

i c ur concern, but... id bet you wont have a problem. there are tons of cars out there pushin that kinda hp with no probs on pump gas. you can always run higher octane fuel for some added stability to slow down the pre ignition if it is a prob.
im far from a "high hp engine genious", but, there are way more variables than comp and/or alum/iron heads that will cause an engine of this caliber to run hot. id guess that lean fuel ratio is a most popular problem.
also, and dont laugh... a good egr system would help a ton for part throttle cruisin'.
as far as the juice variable goes.... yep, itll prolly be a tad hot w/ runnin it. cause o the lean fuel mixture. but, that is for only a short time, it should cool right back down as the fuel mixture richens back up. (ummmm, should)

just food for thought :rolleyes:
:cool: brian

pillowmeto

sounds good
Im just kinda worried im gonna run down the track with a 300 shot and then it will be dentonating all the way back to the pit area, its also going to be street driven alot, much more than the track.
Id just rather take precatiounary measures now than mess up something later
You dont make great engines with one big thing, but lots of little things

MAtt

gdh

I am running the Dart Iron Eagle's and heat is not an issue. 10.5:1 and pump gas btn 91 - 94 no detonation. I also put an L-88 hood on with cowl and heat has never been an issue with this hood, engine generally runs in the 160 range and I have a 180 thermostat. My hp #'s are close to what you intend but I my sb is a 383 stroker.

pillowmeto

sounds good gdh
What are you using for a radiator?

MAtt

Pete79L82

There are many things you can do to control detonation to run 10-1 with iron heads and not have any problems.

To control heat, it is not just a matter of having lower engine temperatures. You have to obtain more even engine temeratures. You can have the temp gauge read 180 but still have parts of the head have over 300 deg. temps. this will cause detonation. To cure this you will need to run external cooling lines from the back of the mainifold to the water crossover and from the water pump to the center of the heads between the 2 center exhaust valves on the exhaust side of the heads. If you need more information on routing these lines let me know.

Next you have to pay close attention to combution chamber design. You want a small tight chamber with high swirl design. If you look at the chamber design of a vortec head it is one of the best "as cast" designs available.

A lot will depend on the cylinder head design itself. I asume you will be useing an aftermarket head to achive those kind of hp numbers. Both World Sportsman II's and Dart Iron Eagles 180cc and up have very thick decks that will help disapate heat. No stock cylinder head will hit the HP or design parameters you are trying to acheive.

Keep your quelch as close to .035 as possible. This goes a long way in controling detonation. If you get over .045 will will have alot of problems with heat and detonation. Be sure to radius any sharp edges on the valve reliefs of the pistons.

Pay very close attention to the ring end gaps. Regardless of what any ring manufacture says, keep the second ring end gap .003 - .004 larger than the top ring end gap. This will keep the top ring much more stable and decrease any oil contamintion in the cumbustion chamber.

Like you said, there is no single cure for heat and detonation, but a lot of little thing that are done together will control it.

gkull

Are you planning on 500 hp without N2O or a 200 hp N/A motor and a 300 shot of N2) :confused:

pillowmeto

I'm aiming for 500hp off the bottle
Not sure if I'm going to hit it, but id like to see 450 by aiming for 500
then a 300 shot on top of that, full forged bottom end and 4 bolts
I'm going to use the vortecs, but they will be full ported and possibly angle ground valves
It will make .600" or slightly more valve lift with 1.94s and 1.50s and solid lifters

Thanks for the tips so far everyone.

Oh, i also plan to fun electric fans, and most likely an electric water pump conversion, the motor that runs the existing pump. the AC compressor is going out, and i think ill use a mid mount plate to hold her down, but i might go front plate.
I'm trying to eliminate all the items that cause drag on the engine
It will also get a crank wipe, baffle and windage tray
Id consider loosing the power steering, but id like to use a hydra boost, but i might not and just use a vacuum reserve canister

Pete, I like those techniquies and ill look into doing them

Also, since it will have a very storng bottom end, in the future i could transfer in some really mean aluminium heads if I want to make even more power

MAtt


[Modified by pillowmeto, 7:17 PM 3/22/2004]

gkull

Only ARP studded with larger billet steel main caps is going to take on 750 - 800 hp.

Cranks/rods/pistons that can withstand that kind of power are expensive and your not going to do with wimpy small valve heads

gdh

Pete mine is right at .035, and you are dead on about the Dart's (mine are the 200's) race ported. We have used temp sensors just to try to ensure that the heads are not getting to hot and everything has been fine, I did find that with the L-88 hood it disipated the engine heat much better than stock. I do have the stock radiator - was recored 2 summers ago.

Simmo

Aluminium heads dissipate heat into the rest of the motor better than iron. Iron holds the heat better in the chamber and thus out the exhaust pipe. This is an issue about detonation not what the temp gague will read.

Pay attention to the quench points mentioned, polish the chambers and run as cool a spark plug as you can. Cold air intake too.

Dumping lots of nitrous on a 500 bhp small block spells disaster unless you really know what you are doing and have had plenty of experience. Up the fuel octane in this instance.

Lt1er

You sound to me like your just a bench racer who doesn't have a clue! Kind of a waste of time even talking to. Your goals aren't realistic and you don't know much about motors. Do you have $8-12K to build this motor and another wade of money to put that power to the ground?

:yawn:

lostpatrolman

Let the guy has his fun without bashing him for it. He will learn from his mistakes. The few runs he gets out of the engine will be a blast.

71coupe

You are probably better off parting with the iron heads & just get a pair of aluminum heads. Not too expensive for a SB anymore & OK w/ 10.5 to 1 c/r.

mandm1200

There was a lot of good info presented here. I worked in a garage many (20+) years ago. Many young bulls wanted a lot of horsepower for the street but did not like to hear what the owner, an experienced engine builder, would do for them. The best advice I can give is to talk to someone who assembles engines for a living. They are not only practical but also realistic. They have built engines according to what the customer wanted and then re-did them because it didn't work the way the customer dreamed (wet?) about. They are only trying to save you from making the same mistakes many others have made. It takes money to build an solid, reliable, performance engine.
Personally, I don't think 10/1 cr is out of the question, 10.5/1 on cast iron heads may be the limit with today's gas. The new vortec heads should allow you to bump up the compression 1/4 to 1/2. Like others have said, make sure there are no sharp edges to get hot and cause detonation. If you haven't purchased the vortec heads, you may want to consider the alum fastburn heads or aftermarket heads. From what I read elsewhere, there is not much to gain by porting the vortecs. If that is the case, put the money you were going to spend on porting and use that towards new alum heads. Get the engine parts you need to get you to your target. If short on cash, like me, just postpone the build.
I know this was a little off topic.
:sad:

Mike


[Modified by mandm1200, 2:16 PM 3/23/2004]

pillowmeto

Thanks everyone
Its still all in the planning process so everything is flexible
I have been thinking about aluminum heads, probably something form AFR
That was part of the reason for this thread
I'm going to start talking to the machine shops soon and see what they can tell me
I don't intend to run a full 300 shot much, maybe once a year at most
I just plan to get a NX kit that can handle a 300 shot and run it at a 100-150, but have the capability of a 300, Id be worried about the 300 shredding my motor and rear end/u joints
The drive train of course will be upgraded
I have a friend who ran a Gen 2 comaro 350 w/ a all stock bottom end, cast pistons and crank, that was never rebuilt. He ran it for 4 or 5 seasons, i don't remember how many, with 8.5 to 1 compression with a 150-300 shot depending on the day :eek:
I was quite surprised it lasted through that.
I have two leads on good machine shops quite close to me and ill give them a call next week or the week after when i have most of it figured out to see what their opinions on the built are going to be.
This is going to be a street motor that will see some track time, as in at most once a month, it will also obviously not be a daily driver, but just a weekend and cruiser car.
In defense of the vortecs, car craft is making 420 hp from then with a roller cam and 1.6:1 rockers and a new intake on a all stock replacement motor from GM rated at 260 hp, it has 8.5:1 compression and the heads are all stock vortecs except for the new rocker ratios

At the earliest i think the car might be ready next summer, but i doubt it, because I'm sure a bunch of things will change and its going to cost alot for things other than just then engine that i will have to do

MAtt

pillowmeto

ARP and billet main caps are in the plan, its a 2bolt block now so splayed is a possibility
Im going to PAW for the bottom end in one of thier packages, which means that they arent name brand :( , and the crank is probobly twist forged :(
It would need to hold 500 hp, even though i probobly wont push quite that, and a 150 shot every 1000-2000 miles
the large valve heads seemed to help mostly in the much higher rpms, where i dont plan to go, ill set a rev limiter, at 7000 and shift around 6 i think, depends on what the torque curve looks like
Because of all of the little accessories that i have been thinging of recently i think its going to be a bit over 3 grand to build

MAtt

gkull

IMO - Read everything you can and get a good plan in place the first go around. You'll save yourself money in the long run.

Take Car rags dyno tests with a bit of skeptical outlook. They are skewed to the highest bidder.

I built my 383 with 800 hp in mind with a 250 shot of N2O. http://www.flatlanderracing.com