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Discussion Starter · #1 ·
you had an 'ideal' rod ratio of 1.75 how much can you then raise the redline too safely? This is assuming all the components are also needed in conjunction to raise your powerband or widen it and support the higher rpm of the engine...

Also, if you had this rod ratio, what are the affects of something like this and adding boost? Would this require a different sized turbo if the engine were also bored to a 2.0l? Because based on most of the threads i read it seems like the ideal turbo size for our engines is the t3's or the hybrid t3/4( I only have a basic understanding of the concepts above from the articles, so if anything i've said needs to be corrected, go for it, also i realize this is also part FI question, but i didnt wanna double post. )
 

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why do you guys want to rev so high all the time?

the higher you rev, the more gears you need just to keep the damn engine in the powerband.

the higher you rev, the less driveable in the low rpms you become.

it's not a coincidence that the Formula one engines that rev to 19,200 rpm need 7 -8 speed gearboxes.

it's not a coincidence that a 24 hr LeMans endurance GTP or LMP turbo V6 with 10,000 rpm only needs a 5 speed gearbox.

it's not a coincidence that when the new F1 regulations limiting 1 race engine for practice, qualifying, and the race altogether will force all the team engines to have a lower redline than last year's version for BETTER RELIABILITY.

it's not a co-incidence that Cosworth who made all the engines for all the teams in CART last year, LOWERED their methanol redlines for reliability and cost savings.

why do you want a higher redline?
 

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for the record, the 1.75 r/s can go to 11,000 rpm quite easily without excessive vibration from sideloading.

the CBR600RR has a 13,500 rpm redline on the street bikes with a similar r/s.

you better have interference fit valvesprings, valvespring keepers, retainers, and rockers that can handle that level of rpms too. they don't have to be titanium either.

You know Comptech (yes the same Comptech that sells us all those aftermarket Teg goodies)built the IRL Chevy V8 in 2002 with a 10,700 rpm redline and used steel retainers? they could have used titanium but the weight difference wasn't worth it? This is the engine that got the pole at the Indy 500 and the one Montoya won in for Team Ganassi. Steel retainers.
 

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MichaelDelaney on Feb/11/04 said:
why do you want a higher redline?
b/c it's...
DuH lol


i'll never understand it either. i guess i've been around too many v8's, b/c i know my ass still clinches whenever i creep much over 6k rpm. unless i'm at the strip, i can go plenty fast enough to impress friends shifting below 6k.

especially with boost... boosted motors make obscene power (for a 4-banger) in low rpms.

anyhow, to answer the question... if you're going to rev a lot, might as well forget boosting. you won't find a decent cam to make power much over 8k rpm, unless you go custom. and yes, you'll need a bigger turbo than a more "normal" setup, as you'll be flowing a lot more air at 10k rpm than somebody revving along at 5k
 

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Discussion Starter · #5 ·
Well, I did not want to go anywhere over 8k, I was just wondering if it's safe, and i figured that if you were reving to 8k you'd be spending more time under boost, and your powerband would not drop off, so in my mind i was thinking this would be a good way to widen the whole powerband... But if there's no point, then I guess I have more reading to do on the subject :)
 

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you don't *need* a perfect r/s for only 8k.

b18c's do it with 1.58 r/s... relatively poor. they can be boosted at that redline. they just have all the goodies to complement a bad r/s ratio.

spending all the money to get a perfect r/s ratio just for 8k is pointless.
 

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Discussion Starter · #7 ·
I was planning on keeping my ls block, but i guess i could look into setting up a ls/vtec, i just figured it'd be easier to boost a ls than ls/vtec and boosting that ( more things to go wrong in my mind )
 

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You wouldn't need to setup an LS/Vtec to change the r/s ratio. Just buy custom rods and pistons. It isn't any easier to boost an ls than an ls/vtec is has just been more common for an engine built by honda to outlast the engine built by jo schmo.
 

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LS/VTEC and turbo...two things that have been beaten to death....do you have any more questions?
 

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Discussion Starter · #10 ·
I know i would not have to setup a ls/vtec to change r/s ratio, and i know the aforementioned topic has been beaten to death, i wanted to know about the rod ratio for personal information, just because i asked dont assume that that's what i'm trying to do, when all im trying to do is continue to further my knowledge. Sorry to have wasted your time.
 

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MichaelDelaney on Feb/11/04 said:
for the record, the 1.75 r/s can go to 11,000 rpm quite easily without excessive vibration from sideloading.


What is the "safest" redline the B18C5 rs ratio can handle without excessive vibration from sideloading? Is there some formula that can be used here?

From reading around, the B18C5 redline is at 8400 rpm with fuel cutoff at 8500rpm. Assuming that a full valve train upgrade has been made, will the engine be able to sustain a 9000 rpm for prolonged periods of time without causing damage?
 

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MD revs past 9000 with the proper upgrades on his GSR with the same rod ratio...
 

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Proxus on Sep/18/04 said:
Quote: MichaelDelaney on Feb/11/04
for the record, the 1.75 r/s can go to 11,000 rpm quite easily without excessive vibration from sideloading.




What is the "safest" redline the B18C5 rs ratio can handle without excessive vibration from sideloading? Is there some formula that can be used here?

From reading around, the B18C5 redline is at 8400 rpm with fuel cutoff at 8500rpm. Assuming that a full valve train upgrade has been made, will the engine be able to sustain a 9000 rpm for prolonged periods of time without causing damage?

The valvetrain isn't the only part of the motor that takes a beating from a high redline. You have a whole other slew of parts that will be affected too, ie pistons/rings, rods, sleeves, etc.
 

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JustinKlemgold on Sep/18/04 said:
MD revs past 9000 with the proper upgrades on his GSR with the same rod ratio...
I have heard this before but because he has reved past the 9000 rpm mark doesnt mean its safe. There is another post by him on some other thread where he says that you can rev any engine to whatever revs you want, but it will take strain.

My question was made with the constraints of using an upgraded valve train and the stock ITR internals (pistons, rods, rings, no sleeves) to see if 9000 rpm was "safe". If the pistons, rods, rings, etc need to change then they need to change. My primary concern here is side loading and longevity of the engine with a higher redline.

I have worked out that 9000 rpm is the better redline for the drive train and powerband setup that I am looking at.
(9300 redline would be ideal with a shift point of 9000 - makes me fall straight back into the targeted powerband and gives me an excellent top end speed)

JustinKlemgold : Do you know what his GSR upgrades are?
 
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