I'm rebuilding my motor as you may know with everything alltogather the compression raito is about 12.6 to 1 idk if my connecting rods would need to be upgraded to forged or not I don't want to get all this done and throw a rod and with that said would I need to go with a better crank or not I would think the crank is ok but idk about the rods any info would be nice
Why are you going to have such a high CR? What are you planning to do with your engine once it's rebuilt? If this is for your daily driver Eagle then I'd say that 12.6:1 is way too high. You going to need 110 octane or higher racing gas. Are you working on this with a shop that's doing some machining for you? If so you should talk it over with them and see what they figure is a safe CR for you to use and what gas you'll want to use.
How ever did you come up with a figure of 12:6 - 1 ?????
I take it you want to run on alcohol? I would upgrade to a forged rotating assembly and ARP hardware throughout the engine, 12:1 is steep and I doubt the stock bottom end would take it in long run.
Quote from: 68AMXGOPAC on May 23, 2011, 11:09:36 AM
How ever did you come up with a figure of 12:6 - 1 ?????
He's building an engine for E85 which has an octane rating of about 105. As far as needing forged or billet rods, I can't give any advice based on experience, however I would assume if you installed ARP rod bolts and had the rotating assembly balanced, you should be fine. Typically you want stronger rods for higher RPM applications. 12.6:1 is the static compression ratio. What you need to worry about is your dynamic compression ratio which is mostly dependent on your cam choice. But if you have the money burning a hole in your pocket, it would be cheap insurance to get stronger rods.
I did not think of you running ethanol or E85. I don't recall ever seeing it available here in CNY. I believe it was common in Minnesota when I was there last year. Will you always be in an area where it is available? Gas around here only contains 10% at this point. Unless someone else in the area has seen it?
Quote from: wagoneerhauler on May 23, 2011, 05:52:35 PM
I did not think of you running ethanol or E85. I don't recall ever seeing it available here in CNY. I believe it was common in Minnesota when I was there last year. Will you always be in an area where it is available? Gas around here only contains 10% at this point. Unless someone else in the area has seen it?
That would be my concern also. Definitely not a vehicle you will be able travel cross country. Closest station to me is at least 30 miles away.
I have an American Motors performance book.They list the requirements for upgradeing thier engines through I think 4 "stages" of performance , I'll see if it says anything relateing to your question. ( forgot I had it ).
easiest set of forged rods ive heard of is actually either a chebby set or i think someone somewhere (not on this forum) was talking about using import rods. but to do that you have to grind the crank pins down a bit but hey, why not add a hair of stroke to it? aside from the fact that will bring your already astronomical CR even higher :-\
Yea I have e85 readly avalable and if I travel cross country I plan on taking a couple 55 gal dums of either e85 or methonal with me that's why I got the cr so high to make the swap to alochol worth wile forged rods really airnt that much more its the forged crank that will break the bank lol I've already got a set of forged flat top pistons and I'm getting a low rmp torque cam shaft and to get 12.6:1 raito I am doing the 4.0 head swap milling the head 30 thousanths putting my combustion chamber at 53cc going 40 overbored pistons a preformance muti layer steel head gasket which is .043 thick and ill be zero decking the block to put me at .043 quinch hight. U can plug the numbers into a compresion raito calculator stroke 3.895 bore 3.79 combustion chamber 53 deck 0 piston volume 0 and it all pans out to 12.6:1 static compression raito
Quote from: Demigawd on May 23, 2011, 07:25:15 PM
Yea I have e85 readly avalable and if I travel cross country I plan on taking a couple 55 gal dums of either e85 or methonal with me that's why I got the cr so high to make the swap to alochol worth wile forged rods really airnt that much more its the forged crank that will break the bank lol I've already got a set of forged flat top pistons and I'm getting a low rmp torque cam shaft and to get 12.6:1 raito I am doing the 4.0 head swap milling the head 30 thousanths putting my combustion chamber at 53cc going 40 overbored pistons a preformance muti layer steel head gasket which is .043 thick and ill be zero decking the block to put me at .043 quinch hight. U can plug the numbers into a compresion raito calculator stroke 3.895 bore 3.79 combustion chamber 53 deck 0 piston volume 0 and it all pans out to 12.6:1 static compression raito
If you're building this purely to run on E85, you really don't need to have a compression ratio that high. That's an extreme difference from stock to modified as far as engine stress, and proper tuning of the fuel system with EFI (which would have cost you FAR less) it will run E85 just fine. My CR is somewhere between 9.6 and 10 but I don't have enough information to make a good calculation, and it runs E85 with no difference in performance over pump gas other than a slight drop in mileage, and i didn't have to build the motor to do it. I'm just sayin, if you want to make it worthwhile, focus on your fuel system, because proper fuel control has far greater effect on compatibility than internal engine build alone. Plus you won't have much cargo room left after attempting to fit 1 drum in the back....BUT. This is just my opinion.
HOWEVER.. Yes, Hesco makes full forged rotating sets, which include ARP bolts, forged crank, forged rods, forged pistons. They're very costly, a few thousand dollars, but if you're going to go with those specs, there's no avoiding a costly build.
LMAO I just stoped laughing at the image of me tring to put a 55 gal drum in my back seat and in the hatch but I have a hitch set up for it I'm going to be installing also so I'm going to get a small trailer to put the drums on I was looking at the 4.060 Stroke crank from 505 preformance they also have forged rods I can get I think there crank is forged and it comes with apr bolts also I may save up and go with that figure if I'm going to do it good I better do it right
Do you know what dynamic compression ratio you are going to be running? Dynamic cr has a lot more meaning than static cr
I believe Scat (www.scatcrankshafts.com) makes V8 rods that might be adapted. Nick Alfano may have some also.
Propane has a high octane number also - some say 103, others 110. Natural gas is supposedly around 130.
I have to get ahold of the people I'm getting my cam from to get some more number but I can figure my dynamic raito in a day or 2
Have you ever towed or carried 55 gal. drums of liquid ?? LOL, not an easy or fun thing when it gets sloshing around,let alone the weight.I would think your adding close to 1,000 lbs. easy with the trailer. BUT , then again , you certainly would have the motor to pull it !!Sounds cool , looks like you have it thought out.
Once this motor is built I wanna see some power numbers :D
Intake closes at 34 degrees after bottem dead center the calculator I'm useing is a bit confusing so its either 10.5 or 11.9 dynamic CR if I got the 4.06 stroke crank its either 11.6 or 12.4 dynamic cr, o and I talked to a friend of mine in flordia that builds jeep stroker motors all day long and he said the stock rods and crank would be plenty stong for the CR ill probably get the apr bolts just to be safe and later when I have the cash ill swap to the 4.06 crank with forged rods
Ok I checked a couple diffren calculaters and its the larget of the two numbers so my dynamic CR with the 3.895 stroke is 11.9 and with the 4.06 stroke it would be 12.4
Quote from: Demigawd on May 24, 2011, 04:40:11 PM
Ok I checked a couple diffren calculaters and its the larget of the two numbers so my dynamic CR with the 3.895 stroke is 11.9 and with the 4.06 stroke it would be 12.4
:o that is some high dcr!
After much reading online and advice from many people I'm just going to stick with the stock rotating assimbly I've came to the conclusion that if I wanted to reach higher rpm's I would need the forged rotation asembly but at that point I would more than likely want to swap to EFI and a full roller rocker and roller cam asembly but since I'm sticking with low rmp torque and probably not going over 4-5000 rmps the cast rotating asemble is going to be just fine :-) yes 11.9 DCR is very high but being ran with ethenal and methenal it will work out as my sweet spot at about 260 psi per cylinder
You could allways have them shot peened and balanced ??I know with the AMC V-8 , it adds to achieve a higher rpm. range.
I was achally just thinking about doing that lol
while it will definately make for a more reliable and smoother running engine, the amc 6's have a crank harmonic that prevents too high rpm, and will actually snap the crank. it looks like if you can rev through it fast youll be fine but staying in that rpm range will definately snap it.
Quote from: 68AMXGOPAC on May 25, 2011, 07:12:59 AM
You could allways have them shot peened and balanced ??I know with the AMC V-8 , it adds to achieve a higher rpm. range.
Good idea. Remove any stress risers and match them weight wise.
Talk about a rolling bomb, WOW, I think you may want to check into the legality of having drums of gas (any kind) in the back of your car. or in a trailer. Most external tanks have to be DOT approved, I don't think a drum falls under that ratting.
Just my thoughts, but good luck with your project, sounds like fun!!
Federal law stats that anyone can carry up to 119 gallon of methanol for personal use without placs or a permit in red plastic drums clearley labeled methanol and two 55 gal drums is only 110 gallons :-) as for my rpm's with the ax15 tranny swap I'm going to do any my tire size ill be going 130 mph at 3k rpms so I really don't think I will need to hit my red line of 4-5k rpm like ever so I won't have to worrie about the crank snapping :-)
If you want to maintain those speeds you're going to need a lot more work than you think. Driving an Eagle to 120 is scary on a stock (or mildly upgraded) front end, and I've upgraded to poly bushings and a sport rear swaybar. You will need to do a LOT of work to that car to make it stable enough to go that fast, and consider that you're dealing with 120 gallons x 8.6Lbs per gallon, which means you won't be able to stop. Our brakes are terrible for coming to a stop from highway speeds, it doesn't take much to get them fading. I've towed 2000+lbs behind mine for decent distances and it has a huge effect on the braking. Also, in order to pull those RPMs at that speed, you would need 2.35 gears and much larger tires than stock. That combination will also break your in town gas mileage and acceleration, and you will need to make a very respectable amount of power in order to even attain those speeds.
Also, the 4.0 head swap will put your power into the midrange, and add tons of top end. If you never make it past the 3500 rpm mark, you're missing out on a lot of power. A 4.0 head swapped 258 pulls hard all the way to 5000 rpm. Keep in mind the 4.0 was tuned to make its maximum horsepower at 4500 - 5000 rpm depending on year and head casting, and max torque in the low 3s.
Also.. getting caught driving more than 100 mph in most states constitutes an automatic arrest and can include felony reckless driving. I lost my license in the past for points and speeding, it's just not worth it. There's no way a policeman would go easy on someone driving that fast in a 25+ year old large station wagon.
I'm not trying to shoot you down, I'm all for people building their dream eagles, just make sure you have all of your bases covered ;)
I really dident expect to go 120 on the highway its already got 27 inch tires on it and right now I'm debating weather to stick with my 2.35 gearing or to swap to 3.08 with a dana 44 swap for duribility and rear disc breaks I am doing the front end also due to some controle are problumes I have right now my lower right controle are is cracked and the upper left one is well idk how its holding togather still really swapping to poly bushing and I would only be towing the barrels for cross country driving not for everywhere I go there's plenty of e 85 stations around where I live. The head swap makes it ezer for the motor to breath I'm not taking the 4.0 cam which would put it at mid range rpm I'm swapping to a even lower range cam than stock it will be very torque in the range's I'll be running it I wish I could find some better quality ring and pinnon gears for the 2.35 if I could id much reather stay with the lower gearing gives me better highway milage lol cruzing at 1.5k rmp's running 65 mph I wonder if the motor will have the backbone to pull that off. I do have high hopes for my bird after I get the motor broke in ill have it dyno'ed and run strait here to post the results :-P