ok, first off...this is just an idea, i doubt i'll do it simply because of the cost of the custom pistons and rods but its just busy work, and food for thought.

its all in the rod ratio.


the rod ratio is the measurement of the length of the rods (srt = 5.94" or 151mm) vs. the length of the engine's stroke (srt = 3.98" or 101mm). rod ratio is found by dividing the length of the rod by the length of the stroke. so the stock 2.4L SRT block in this case has a rod ratio of about 1.5:1, which is quite bad. a lot of all out drag 4 cylinders have a rod ratio of no less than 1.8:1. the distance the piston actually moves down the bore is figured by the stroke of the crank alone. both the speed, and the acceleration of the piston are formed by the rod ratio. the reason for changing the rod ratio is this: it has to do with how the rod moves as the crankshaft turns...a longer rod will have a smaller angle of defelction than a shorter rod at the same stroke. not noticeable when half way between TDC and BDC. the smaller the angle, the less the rod has to rotate on the axis of the wristpin, and more force from the piston is applied downward on the crank, so more torque. the piston acceleration and speed have obvious effects on performance of an engine, faster piston acceleration puts more strain on the main and rod bearings and limits the bottom end's rpm limit (maybe thats why the srt-4's redline is so low)

so, on to the point of all this: can i use a longer rod to decrease piston acceleration, and by doing that, will i build a bottom end capable of handling higher rpms reliably? lets see...

the answer is somewhat discouraging.

this is what i was thinking...extend the rod in the 2.4L from 151mm to 159mm, i have some excel tables that show piston speed at any crank angle, it really only matters at 0 though. it shows slight drop in acceleration and also holds the piston at TDC for longer. the acceleration is only brought down by about 1.0% after all the work to lengthen the rod. these results arent what i expected, even with a rod ratio of 1.8 the redline wouldnt be significantly raised. however, according to this 1.0%...if the prevous redline on it was say 6500, now it can be about 6565, woopty do.

stock 151mm:



long rod 159mm:



depending on the application, its not worth all this effort. (at least on the basis of a higher redline) there are however other reasons for a longer rod.

a rod thats longer will always reduce side wall loading, which is one reason why long rods are thought of.



longer rods also cause the piston to 'dwell' longer at top dead center which can work with combustion pressure to produce more work on the crank, more torque at a given crank angle (i.e- 90) this is all relative of course to how much combustion force is on the piston, but im just keeping it constant. this is all needless on a boosted motor, just turn up the boost. but thats not the point, im bored and i need to do something lol. ok. finishing up

the only way to find the ideal rod length (or rod ratio) is if the exact combustion pressure known as to where the piston is. some people actually prefer shorter rods on v8 apps because of the fact that most torque will be made when the crank force and the combustion force curve on teh graphs have the same shape, leaning more toward the TDC side, it makes sense to want the force curve towards top dead center because on a typical high perf engine, the last 70 degrees about of the power stroke doesnt directly contribute to torque. knowing the combustion pressure is not easy to come by...and its even harder because this combustion pressure depends on where the piston is. afterall, ignition occurs before TDC and peak cylinder pressures occure slightly after TDC, but not before. and as much as i'd love to be inside my engine i cant be. i think it basically comes down to trial and error. which sucks, but its just something to think about.




PLEASE feel free to correct anything i might be confused on or anything, any and ALL input is awesome


p.s- happy 4/20










_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

*Skrilla
"Honest officer, I thought you were trying to race me"
Talon: 1st 2.4L
'97 Prelude
'04 350Z

Originally posted by etx
Good luck man! Project 'STFU Brian your talon is dead meat' should be on it's feet soon!

Why didn't you post this in the long rod thread in the advanced forum? Seems to have some good info in there.

__________________________________________
~Chris
03 SRT-4

__________________________________________
~Chris
03 SRT-4

talkin to cheesefrog....he was givin me some dank ideas

"Hmm a 101mm stroke and 151mm rod length. 1.49 ratio... that explains the low redline. Would be cool if you could raise the head about 20mm with a deckplate and correspondingly longer rods and get that RS ratio to around 1.69. Then you could spin to 10k without having to worry about throwing a rod through the side of the cylinder wall"


_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

Well, if you want a longer rod, feel free to use a deck plate and either sleeve the block or lower the top ring. I, myself, however, would probably destroke the crank a little bit. Higher RPMs allow bor better use of gearing.

That being said, I'm a hypocrite. I am using a motor with an iffy (at best) rod:stroke ratio, and a LOOOOOOOONG stroke. Hell, I like torque.

Since I like torque, I also don't mind a shorter rod. It will suck harder from 10* until 90*, and less hard from 90* to BDC. Furthermore, while you can take your dwell time at TDC, I'll take my dwell time at BDC. Why? So I can open my exhaust valve earlier. Also, the intake valves can close a bit later without pumping cylinder air back into the intake manifold. Lastly, and this is the best part, the mechanical advantage of a short rod over the crank journal is much greater then that of a long rod. At the cost of more cylinder side loading, more torque can be had. If the motor is made out of decent materials, I wouldn't worry too much about cylinder wall erosion or piston sideskirt erosion. Especially with the Moly coating on the skirt of the SRT-4 pistons.

Besides... What marque of motor is the paragon of high-revving? Yeah, Honduhs. A B16 has a rod:stroke ratio of 1.52, and some Honda motors have a 1.48 rod:stroke ratio! I think that the stroke is what does the revlimit on the SRT-4 the most damage. If you want the 2.4L motor to rev higher, I think you are just going to need to destroke the crank.

Now, is it possible that the Honduh blocks can rev so high because of their flimsy open deck/unlocated sleeves/aluminium block allowing enough flex to compensate for the problems with short rods? I'm just taking a shot in the dark, because I REFUSE to believe that they rev so high because of magic.

Now, I think we all had enough discussion and flaming on this topic from the older threads, but I eagerly await EVERYBODY to come out and tell me I'm wrong again. Including the Tool. And then I can explain my position, and get flamed some more. Good times ahead!

-=B-=

Dude, Boeing called. They want their wing back.

Dark0ne95: There is a butthole on that girl that his going to feel the wrath of 23 yeras of worldwide hate.
Me: Can I put that in my sig?
Dark0ne95: GO right fucking ahead.

i actually read all that. interesdank indeed.

Having Problems? Heres my Three step solution to anything 2gnt related.
Step 1: Put down everything in your hands.
Step 2: Grab a lucky strike, Smoke it.
Step 3: Walk to the fridge, double fist some keystone ice, sit down in the shade, drink one beer, finish cigarette, drink other beer, roll a joint, smoke it, walk back to your problem, and in about 5 minutes the solution will come to you.
If not. Go here: here

If still nothing, your trying to hard. Start over at step 1.

*Skrilla
"Honest officer, I thought you were trying to race me"
Talon: 1st 2.4L
'97 Prelude
'04 350Z

Originally posted by etx
Good luck man! Project 'STFU Brian your talon is dead meat' should be on it's feet soon!

the tsx has a 4 cyl 2.4L with a 87mm bore and 99mm stoke and redlines at 7100rpm, makes about 200hp NA and 166ft lb's
_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

Hondas rev so high mostly because they can. Do you think Joe Ricer cares about his rod ratio? No, but he'll take it to 9000RPM on his hacked ECU as often as he can. Do they scatter? Sometimes. More often, probably not.

You can't just look at the numbers and expect anything to match what you see in practice. Materials, balance, and construction have a lot to do woitj it, just as much as the numbers do.

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

The board died on my the first time I tried posting to this. Just as well, it was something lame and sarcastic. I ended up learning a lot in here. Thanks guys.


And someday there may be a 2.4L in Daisy. I just want there to be a lot of experience with installing them before I take that road. I don't need to be having shit in my daily driver breaking all the time due to a hack install.

Dank you all very much. (Since dank seems to be the word du jour)

2.4 2.4 2.4 2.4
Turbo I had a dream last night. There was this mountie....and he had stolen your 2.4 to give to me. Then we smoked some of your DANK you were telling me about. He stole that too. lol

I eat emo kids for breakfast

1995 Eagle Talon (SOLD)
72' SuperBeetle
72' Standard Beetle
56' Deluxe Beetle

alrighty then! found out some GOOD info! the mopar stage 2 kit actually brings the redline on a srt to 6500, and MANY people have turned the stock block over 7250. i was talking to some of the guys over at srt forums and we were just discussing upgrading the valvetrain would be the only need-to when wanting to turn that high of rpm's. so 7250 it is
_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

I don't think that the valvetrain is the absolute limit with the 2.4... Perhaps it is on the 2.0, but the stock bottom end on the 2.4 would take a dump before the valvetrain. That being said, it's not impossible to break valvetrain parts with a 2.4 and stock cams, but if they DO break, it's fate. Safe bet to upgrade the valvetrain at the earliest convenience, though.

-=B-=

Dude, Boeing called. They want their wing back.

Dark0ne95: There is a butthole on that girl that his going to feel the wrath of 23 yeras of worldwide hate.
Me: Can I put that in my sig?
Dark0ne95: GO right fucking ahead.

Originally posted by turbo8u
alrighty then! found out some GOOD info! the mopar stage 2 kit actually brings the redline on a srt to 6500, and MANY people have turned the stock block over 7250. i was talking to some of the guys over at srt forums and we were just discussing upgrading the valvetrain would be the only need-to when wanting to turn that high of rpm's. so 7250 it is _________ 96 talon esi-t san clemente, ca as needles of ice are the ill winds' talons the coldest of shadows they seep unto the bone silent souls leave .308 holes

*Skrilla
"Honest officer, I thought you were trying to race me"
Talon: 1st 2.4L
'97 Prelude
'04 350Z

Originally posted by etx
Good luck man! Project 'STFU Brian your talon is dead meat' should be on it's feet soon!

Just so you know, HRC spun the 2.4L in their Neon way beyond 7000RPM. I think i heard them say it bounced up to 9000 between shifts. That car had a LOT of passes too, and they never lost a bottom end from the high revs.

Crower rods, JE pistons. Saw it myself... Just food for thought.

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

a lot of the guys over at srt forums are HELPFUL . ive been talkin to a lot of them lately and they said basically, yea...it will definately redline that high but without some different cams you'll be choking it out. also, changing the valvetrain parts for our head is probly a good idea like bill said, at the most convenientt time possible. crane 18 cams would be pretty sweet too. i was just worried about having a 7250 redline in the 2gnt ECU and having a block that could only wind up to 6000, but now i know it can go higher that was the whole point of this thread anyway

thanks guys its good to know i have some people around who actually know wtf they're talking about, try going on a honduh board and talk about somethin like this....or fuck...dsm tuners for that matter

skrilla, when are we doin your swap dude?
_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

Originally posted by turbo8u
a lot of the guys over at srt forums are HELPFUL .

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

Originally posted by turbo8u
a lot of the guys over at srt forums are HELPFUL . ive been talkin to a lot of them lately and they said basically, yea...it will definately redline that high but without some different cams you'll be choking it out.

Originally posted by turbo8u
i was just worried about having a 7250 redline in the 2gnt ECU and having a block that could only wind up to 6000, but now i know it can go higher

*Skrilla
"Honest officer, I thought you were trying to race me"
Talon: 1st 2.4L
'97 Prelude
'04 350Z

Originally posted by etx
Good luck man! Project 'STFU Brian your talon is dead meat' should be on it's feet soon!