iron eagle to afr heads
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iron eagle to afr heads
hey guys pulling the motor out of my car cause it needs a good going through. while its out im going to install the long tubes on it and thinking about swaping heads.
the motor now is a 383 stroker about 10:1 compression xe274h comp cam dart iron eagle heads (72cc chamber 180 intake runners with 2.02/1.60 valves) performer rpm intake and a holley 750 up top.
my thoughts are about swapping to afr heads with 195cc intake runners and 75cc chambers. ill save some weight and hopefully let it breath a little better up top. my only concern is the motor now makes gobs of torque and I love it. drives daily like a dream (for a hopped up sports car that is)
just wondering what you guys thought good idea/bad. if it aint broke don't fix it etc. etc.
the motor now is a 383 stroker about 10:1 compression xe274h comp cam dart iron eagle heads (72cc chamber 180 intake runners with 2.02/1.60 valves) performer rpm intake and a holley 750 up top.
my thoughts are about swapping to afr heads with 195cc intake runners and 75cc chambers. ill save some weight and hopefully let it breath a little better up top. my only concern is the motor now makes gobs of torque and I love it. drives daily like a dream (for a hopped up sports car that is)
just wondering what you guys thought good idea/bad. if it aint broke don't fix it etc. etc.
#2
Re: iron eagle to afr heads
Depending on where you are on the quench,you could go with aluminum heads to 10.5 on pump gas,but 75CC's ant going to cut it.The 195's are going to move your torque curve up,but given the 4.11's,it should be all good with a matching cam to the SCR.It then becomes a question of how high in the RPM are you going to spin it and what the bottom end you own that can handled it safely.
I went the same route(sort of)as you for Iron Eagles 180cc's.But I decked to block,matched the pistons,and cut the heads to 67cc's for a good quench number and SCR.
I went the same route(sort of)as you for Iron Eagles 180cc's.But I decked to block,matched the pistons,and cut the heads to 67cc's for a good quench number and SCR.
#4
Re: iron eagle to afr heads
This thread is a prime example of how people can and should tailor a power curve for a intended use.The idea of people who do things because everyone else does is a poor excuse for a bad build plan.The positive side of that statement is all intake runners of the same size are not equal from different companies.The fact the cross sectional size and shape of a port does make a huge difference.
So for ET racers that want to 60'/330' where a bulk of ET is made,torque is important and in the same hand for a game plan to run a car out the back door for mph a tailor build in higher rpm for mph,a build plan should be made for that.
In the same hand,torque is king on the street driven vehicles. It is a power curve that presses the flesh against the seat.
Point being two fold.Iron RHS VS AFR's are not even in the same church or pew.Bigger is not always better either.All of it depends on the intended use.
Lastly,if you go up in intake runner,you will move that power curve up and to capitalize on that much is dependent on what is in use after the flexplate or flywheel.
So for ET racers that want to 60'/330' where a bulk of ET is made,torque is important and in the same hand for a game plan to run a car out the back door for mph a tailor build in higher rpm for mph,a build plan should be made for that.
In the same hand,torque is king on the street driven vehicles. It is a power curve that presses the flesh against the seat.
Point being two fold.Iron RHS VS AFR's are not even in the same church or pew.Bigger is not always better either.All of it depends on the intended use.
Lastly,if you go up in intake runner,you will move that power curve up and to capitalize on that much is dependent on what is in use after the flexplate or flywheel.
#5
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Re: iron eagle to afr heads
Bigger isnt always better but in this case that motor will wake up. The eagle 180's are crap out the box. I dont have data on the csa but for a 2.02 valve flowing 208-220 cfm isnt great. Csa i would expect to be around 1.8-1.85 sq.inch and the Afr is only marginally bigger at 1.96 sq inch. Yet afr flows 280 thru a 2.05 valve without much increase in volume. That means more port velocity and velocity is what makes torque and fills cylinder. Cam and intake on that 383 want to go to 6k rpm. Let it eat with a head that will support it.
Even dart shp 180 aluminums would wake up that motor
Even dart shp 180 aluminums would wake up that motor
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Re: iron eagle to afr heads
Good up grade for sure. ID do 65cc chamber. Close to 11:1 comp would be nice.
This combo should have a 4000 stall. With your trans and gear/sticky tires..it will be nearly untouchable on the street from 0 to 100mph... Hard launching setup! Goodluck!
This combo should have a 4000 stall. With your trans and gear/sticky tires..it will be nearly untouchable on the street from 0 to 100mph... Hard launching setup! Goodluck!
#7
Re: iron eagle to afr heads
Hey guys I have a 92 firebied with a 305 TBI and I want to swap it out with carb'ed 350 and wanted to know if it was possible to do and what all do I need to do it
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#8
Re: iron eagle to afr heads
AFR certainly has found the "sweet spot" that has help a ton to build their rep.and again people don't realize they can and should buy into either AFR's or Brodix's bare castings fairly cheaply.Then fill them with their choice parts.
In terms of RHS 180's,when I went that route,it wasn't by any mistake.It was intended for a specific type of build and based off RHS's long history in R & D.Those heads you can get in different stages and to have RHS port them is a good thing in deed.
The better companies are "wet" bench testing their heads which is one hell of alot closer to the real deal in use of A/F mixtures over just air bench testing.Fuel does have a wt to it and it does effect the air dynamics in flow.This is where the companies experience in yrs of being in business with a strong R & D program to match those yrs shine.
As always.Anytime a company said they are "as good as",it is the company being compared to is what you need to grin and bear the extra costs to buy.
In terms of RHS 180's,when I went that route,it wasn't by any mistake.It was intended for a specific type of build and based off RHS's long history in R & D.Those heads you can get in different stages and to have RHS port them is a good thing in deed.
The better companies are "wet" bench testing their heads which is one hell of alot closer to the real deal in use of A/F mixtures over just air bench testing.Fuel does have a wt to it and it does effect the air dynamics in flow.This is where the companies experience in yrs of being in business with a strong R & D program to match those yrs shine.
As always.Anytime a company said they are "as good as",it is the company being compared to is what you need to grin and bear the extra costs to buy.
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Re: iron eagle to afr heads
thanks for the input guys. deffinatly makes the decision easier. id go with the 65cc heads but I like being on the safe side when it comes to running pump gas. as far as the bottem end goes its an eagle cast unit. I beam rods hyper pistons etc. etc. pistons are likely to change it is coming out for a rebuild after all.
I know the larger heads will move the torque curve to the right but it makes so much down low I really don't think im goin to miss it espically with a 3k stall.
oh and as far as the hard launches on the street ask my fourth gen friends how much I spin with my drag radials on hahahaha.
I know the larger heads will move the torque curve to the right but it makes so much down low I really don't think im goin to miss it espically with a 3k stall.
oh and as far as the hard launches on the street ask my fourth gen friends how much I spin with my drag radials on hahahaha.
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Re: iron eagle to afr heads
bc yes it is possible. mine was originally a 91 tbi car. basically all I did was put in a fuel pressure regulator for the carb and youl have to do something with the ignition. weather it be msd or and hei unit. pretty sure that's all the major changes I had to make.
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Re: iron eagle to afr heads
thanks for the input guys. deffinatly makes the decision easier. id go with the 65cc heads but I like being on the safe side when it comes to running pump gas. as far as the bottem end goes its an eagle cast unit. I beam rods hyper pistons etc. etc. pistons are likely to change it is coming out for a rebuild after all.
#12
Re: iron eagle to afr heads
ok thanks a other question the 350 that I have is a Chevy and I'll it bolt up the same on my firebird and will my gauges work
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Re: iron eagle to afr heads
I don't think Ill lose to much compression. depending on how the block looks it might end up a .040 over block. it has 72cc heads now I wouldn't think 75cc would make that much difference. and im sure the block will need decked again. after all it is a sbc.
#15
Re: iron eagle to afr heads
Get the block/pistons settled in before any choice in heads.
Also if pistons are needed,consider the "D" dish pistons.They give you excellent quench numbers at 0 deck.
Also if pistons are needed,consider the "D" dish pistons.They give you excellent quench numbers at 0 deck.
#16
Re: iron eagle to afr heads
will I have to eliminate some of the sensors and what do I do with the ecu
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Re: iron eagle to afr heads
I pretty much rewired a good section of the car. running a carb and a separate ignition set up just through the thing away. I put my 6al in the slot for the stock ecu if that tells you any thing. sensors like the oil pressure and water temp go straight to the gauges in the dash. that really is all there is to it.
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Re: iron eagle to afr heads
Oh another thing it always pulled real good up to the 6100 pill. I want to shift it around 6/6200 with a 6500/6700 pill in it. Do you guys think my eagle sir I beam will be OK for that or should I just drop some h beams in there now?
#22
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Re: iron eagle to afr heads
i would probably keep everything the same, especially if its balanced already. im thinking an n/a 383 turning 6200 with those parts will probably be ok. hyper pistons are great for what you are doing.
otherwise, i would swap everything out in favor of forged parts, go with 210-ish heads, and turn it 7k+. and then spray it. lol
otherwise, i would swap everything out in favor of forged parts, go with 210-ish heads, and turn it 7k+. and then spray it. lol
#23
Re: iron eagle to afr heads
Gonna make a blanket statement.A forged anything internal balanced rotating assembly is more durable.And not a spin term of forged cast steel,but a true forged assembly.
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Re: iron eagle to afr heads
well im pretty sure its going to need at least one rod. been making a noise ever since I hydro locked it. weather or not anything is wrong with the cylinders will determine if I bore it and need pistons.
I checked my dynamic compression compared to now and with 64cc heads. with a 10.7:1 static and my cam it comes out to 8.4ish. how will that hold up to pump gas?
I checked my dynamic compression compared to now and with 64cc heads. with a 10.7:1 static and my cam it comes out to 8.4ish. how will that hold up to pump gas?
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Re: iron eagle to afr heads
Just ran across this thread....boy does some of this stuff sound familiar!!
#26
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Re: iron eagle to afr heads
For a real pump gas street engine with iron heads I think the best bet is to keep the DCR less than 8:1. Add a half point to the DCR if the heads are aluminium.
For what it's worth, a change in compression by one full point may yield about a 4% difference in output in a 400+/-hp engine, all else being equal. If the compression is too high, and the optimum timing has to be reduced to compensate, then power drops off dramatically. Much more than 4%.
Here's a great paper on the subject.
Engine Basics.doc
Last edited by skinny z; 04-19-2014 at 07:08 AM.
#27
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#28
Re: iron eagle to afr heads
Skinny.Your situation still has me scratching my head.Not paper proof,but in real life we have build 8.5 DCR engines without concessions.Off hand the only thing I can think of is in your local area your gas must be real crappy.Same brand gas can vary a bunch in the same town let alone from one region to another.
#29
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Re: iron eagle to afr heads
Skinny.Your situation still has me scratching my head.Not paper proof,but in real life we have build 8.5 DCR engines without concessions.Off hand the only thing I can think of is in your local area your gas must be real crappy.Same brand gas can vary a bunch in the same town let alone from one region to another.
Even on 100 octane fuel, with timing reduced it still knocked. Swapped carbs too. Cranking compression was 205 psi on average. Not unreasonably high I thought.
Interestingly after a tear down, there were no visible signs of spark knock. Nothing on the plugs and nothing unusual in the chambers or piston tops. With a little machine work on the heads, about 2 cc was removed (64 to 66) and I've opened up the piston to head clearance by .013" with a thicker head gasket (goodbye .040" quench). SCR now at 9.85 and DCR at 7.9. Tests will resume once my new rockers are installed and the correct length pushrods determined.
My apologies for the thread jack however there is some relevance to the OPs situation.
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Re: iron eagle to afr heads
Interestingly after a tear down, there were no visible signs of spark knock. Nothing on the plugs and nothing unusual in the chambers or piston tops
#31
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Re: iron eagle to afr heads
The lack of evidence is probably from not beating on it terribly hard while trying to tune. Rarely, after matting it would I keep into the rpms for any duration but then again maybe I overlooked some indication that it was pinging. Perhaps that saved it too.
At any rate, it loks like the move paid off. Time will tell. I've got a dyno session booked in a couple of weeks and then off to the track before I drive cross country (again).
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Re: iron eagle to afr heads
allright more questions lol.
ill be doing some measuring when I get everything back from the machine shop as far as deck height and compression ratio. im looking at afr 195 eliminator heads and what I know is this. right now a 65cc head is too small for my liking and that's if the block doesn't need decked. however even if I zero deck the block which it isn't now a 75cc head is too big anybody tried milling afr heads to get a smaller combustion chamber.
and yes 65 and 75 cc are the only options with 195 cc intake runners.
ill be doing some measuring when I get everything back from the machine shop as far as deck height and compression ratio. im looking at afr 195 eliminator heads and what I know is this. right now a 65cc head is too small for my liking and that's if the block doesn't need decked. however even if I zero deck the block which it isn't now a 75cc head is too big anybody tried milling afr heads to get a smaller combustion chamber.
and yes 65 and 75 cc are the only options with 195 cc intake runners.
#35
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Re: iron eagle to afr heads
Just catching up on this again.
You're wanting to choose between the 65 and 75 cc chambers is that right? And keep the current flat tappet 274 cam?
Have you gone any further determining if you'll need an overbore or a decking?
Do you have all of the cam specs? Advertised duration, LSA and ICL? I couldn't find them.
The difference between the two chamber volumers with all else being equal would be alittel over a full point. That is, ~ 9.86 vs 10.96:1.
I wouldn't hesitate for a minute to run 11:1 with the aluminum heads but if the cam timing is too short you could have trouble.
You're wanting to choose between the 65 and 75 cc chambers is that right? And keep the current flat tappet 274 cam?
Have you gone any further determining if you'll need an overbore or a decking?
Do you have all of the cam specs? Advertised duration, LSA and ICL? I couldn't find them.
The difference between the two chamber volumers with all else being equal would be alittel over a full point. That is, ~ 9.86 vs 10.96:1.
I wouldn't hesitate for a minute to run 11:1 with the aluminum heads but if the cam timing is too short you could have trouble.
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Re: iron eagle to afr heads
I'll grab my can card and give the specs when I get home. Doesn't need bored not sure on the deck yet. 65 cc puts me at 10.6:1 if it doesn't need decked. 75 cc puts me at 9.54:1. I just want to mill the heads to around 72 cc. Keep my compression the same as my iron eagle heads.
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Re: iron eagle to afr heads
.4900.490 lift int open at 29BTDC close at 64 ABDC. Exhaust open 75 BBDC close 30 ATDC 230/236 duration
#38
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Re: iron eagle to afr heads
LSA? ICL?
Do you have part number or a grind number?
Do you have part number or a grind number?
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Re: iron eagle to afr heads
LSA is 110.0
ICL 106.0
part number 12-246-3
grind number CS XE274H-10
ICL 106.0
part number 12-246-3
grind number CS XE274H-10
#40
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Re: iron eagle to afr heads
Trying to achieve a decent DCR of around 8:1 is workable with the 75cc heads and a quench of .040" See the attached screen shots.
On the downside, you'll be seriously down in compression should you ever want to step up in cam profile and really take advantage of the AFRs.
On the downside, you'll be seriously down in compression should you ever want to step up in cam profile and really take advantage of the AFRs.
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Re: iron eagle to afr heads
I wont change cams until ive got a forged bottom end at which point domed pistons are easy.
and my static compression wont be that high. my block isn't zero decked.
and my static compression wont be that high. my block isn't zero decked.
#42
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Re: iron eagle to afr heads
I was using the best case examples. Without all of the details there's no telling what you might have for a compression ratio.
The point here was that if you can achieve the values in the chart, then that's what you would end up with. If you can't realize that SCR, then you're not as likely to be happy with the results.
The point here was that if you can achieve the values in the chart, then that's what you would end up with. If you can't realize that SCR, then you're not as likely to be happy with the results.
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Re: iron eagle to afr heads
that's why I was asking if I could mill the heads. I know ill end up with 10.6 compression with the 65cc heads and about 9.5 with the 75. Id like to be some where between 10 and 10.25. then again what does half a point of compression do.
#44
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Re: iron eagle to afr heads
It's the compression ratio combined with the cam that makes up your assembly target.
Remember that one of the most important things you can do at this point is select a static compression ratio that will work with the cam you have. The relatively short 274 cam may build too much compression pressure with a static ratio greater than around 10:1. I know from experience that you're close.
What's half a point of compression worth? About 2% in potential output if it's too low. Something undriveable if it's too high unless you kill it by pulling out the timing. I've just gone through this with a 10.4:1 SCR/ 8.3 DCR albeit with iron heads.
As for milling the heads, absolutely it can be done. AFR has the specs right on their website for amounts milled vs cc reduction.
Last edited by skinny z; 04-28-2014 at 01:39 PM.
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Re: iron eagle to afr heads
5cc dished piston with a .016 piston to deck clearance.
however I got the last of the pistons and rods out today (worked all weekend) Ive got one bent rod and a few messed up pistons.
ever see a wrist pin beat the crap out of a retainer and mar the piston? had to tap the wrist pins out with a punch.
however I got the last of the pistons and rods out today (worked all weekend) Ive got one bent rod and a few messed up pistons.
ever see a wrist pin beat the crap out of a retainer and mar the piston? had to tap the wrist pins out with a punch.
#46
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Re: iron eagle to afr heads
Sorry about your luck regarding the rods and pistons. It sounded like you were prepared for that eventuality though.
That said, what direction do you intend to go now?
New pistons... possibly the D-dish the Gary mentioned.
Rods...maybe Scats 7/16" cap screw stroker versions.
Now you're at these cross roads, will you still stay with the little flat tappet 274 or step up to a hydraulic roller with a little more duration and a lot more lift?
I suspect making 450 hp with the AFR 195s and a decent cam isn't going to be too difficult. And the low engine speed torque shouldn't be diminished to any great extent provided that you keep the cam specs under control and have a compression ratio to match.
That said, what direction do you intend to go now?
New pistons... possibly the D-dish the Gary mentioned.
Rods...maybe Scats 7/16" cap screw stroker versions.
Now you're at these cross roads, will you still stay with the little flat tappet 274 or step up to a hydraulic roller with a little more duration and a lot more lift?
I suspect making 450 hp with the AFR 195s and a decent cam isn't going to be too difficult. And the low engine speed torque shouldn't be diminished to any great extent provided that you keep the cam specs under control and have a compression ratio to match.
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Re: iron eagle to afr heads
well the motor sees a lot of street time and the 274h has great street maners and ive seen two magazine builds now with that cam and the 195 eliminator heads pushing horsepower and torque above 450 which would make me plenty happy. ill sacrifice a little on compression based again on its a street motor so 75cc chambers and .030 over forged flat tops with 4cc valve reliefs from probe.
as far as rods go. peace of mind goes a long way. so scat h beams it is.
time to have the 383 I wanted when I was a broke college kid.
as far as rods go. peace of mind goes a long way. so scat h beams it is.
time to have the 383 I wanted when I was a broke college kid.
#48
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Re: iron eagle to afr heads
However that said, lets look at where you might be heading.
First the 65 cc head.
Let's say you go with the next overbore at .040" and the 4cc flat top piston.
Standard length rods at 5.7".
You mentioned having a .016" piston to head clearance (with your current pistons) and will likely be the same with the new pistons provided you get them with the same compression height.
Combine that .016" clearance with an .026" gasket (Cometic/ Victor Reinz 5746) and you get a nice tight .042" quench.
That'll put your SCR at 11:1.
Add the short duration numbers of your 274H (274/286, 110 LSA, 106 ICL) and the DCR is 9:1.
That's race fuel territory.
Even a .040" thick gasket (which pushes your quench to .056") the DCR is 8.7:1.
Make the move to a 75 head and the numbers are:
SCR 9.95:1
DCR 8.1:1
Although the SCR appears low, especially for an aluminum head, it's the running compression (DCR) that's the more important number. 8.1:1 is getting up there but still reasonable (especially with aluminum).
If or when you step up to a larger cam (and it's inevitable in most cases) then there will be a need to bring the SCR to meet the requirements of the increased duration. You could then have the heads milled and all that goes along with it.
Food for thought.
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