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View Poll Results: What's your Rev limit?
<7,200 24 42.11%
7300 7 12.28%
7400 9 15.79%
7500 6 10.53%
7600 0 0%
7700 0 0%
7800 5 8.77%
7900 0 0%
8000 1 1.75%
>8000 5 8.77%
Voters: 57. You may not vote on this poll

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Old 01-27-2015, 03:08 PM   #1
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Default What is your Rev Limit Set at?

What is your Rev limiter set at? Please vote!
Built engine?
Engine specs: If so, please post relevant specs (pistons, rods, valvetrain, etc)
Do you track the car? On a 1-10 scale, how much hell do you give it?

I wanted to see what everyone is running for there rev limit. I used to run 7900-8000 RPM limit, and never had any RPM related problems other than valve float. But I want to bump that up some. My last motor I reved it to 8700-8800 about 300 times within 700 miles and it didn't like that, so I'm guessing I need to stay below Formula 1 piston speeds to maintain some level of reliability. The head seems to have been fine though!

For me:

Rods-only engine.
RPM Limit: 8000
Built engine: Rods only
Engine Specs: Rodsy only
Track the car: 9/10, Drag race sometimes, mostly street car
Avg number of times your car sees redline/day: 10

Last engine
RPM Limit: 8800
Built engine: Yes
Engine Specs:Rods, full valvetrain, ported head, cast pistons
Track the car: Drag raced, about 50 passes.
Avg number of times your car sees redline/day: 7/day till I wore the bottom end out after 700 miles/50 passes.



Blank one for convenience.

RPM Limit:
Built engine:
Engine Specs:
Track the car:
Avg number of times your car sees redline/day:
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Old 01-27-2015, 03:13 PM   #2
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For my new engine, it will have carillo H-beams, FM forged pistons, balanced, ATI Damper, fully built head that's turned 8,800 before without a failure. What RPM limit should I set to keep it reliable? I want to go to about 8,500 but I don't know if there are any miatas running that reliably?
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Old 01-27-2015, 03:20 PM   #3
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On the block end of things the limiting factor is going to be mean piston speed right?

7000 rpm = 3904 ft/min
7500 rpm = 4183
8000 rpm = 4462
8500 rpm = 4741
9000 rpm = 5020

What do you guys think the safe limit is for stock block and for a forged internals block?
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Old 01-27-2015, 03:28 PM   #4
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Interesting link: Engines with the fastest piston speeds | HondaSwap

From it, engine 3, Honda B18C5
Bore/Stroke: 3.19" X 3.43" (81mm x 87.2mm, more stroke than a BP!)
Redline: 8400rpm
Piston Speed: 4802 Ft/min
Wikipedia says Redline was 8,400, but fuel cut was 8,500.
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Old 01-27-2015, 03:44 PM   #5
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RPM Limit: 8500
Built engine: Yes
Engine Specs: Trackspeed VVT motor, supertech valves and pistons, Manley H beams, ACL bearings, BE street/strip pump, 949 damper, stock SOBs, Supertech heavy singles, junk2 throttle body
Track the car: auto-x
Avg number of times your car sees redline/day: depends on the course, I estimate the motor has spent about 5 minutes over 8300 rpms (about 2 of that is on the dyno) in its about 10 hours of run time.

I just finished re-shimming and installing the inner supertech springs. The intake valves all tightened up considerably in that time and I'm going to keep a closer eye on them. A couple other auto-xers have had problems with dropping intake valves with similarly built motors after about the same amount of re-shimming I had to do.

Last edited by Leafy; 01-27-2015 at 04:44 PM.
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Old 01-27-2015, 04:42 PM   #6
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RPM Limit: 7000
Built engine: yes
Engine Specs: 1.6
Track the car: yes. HPDE/TT/20 min. W2W races.
Avg number of times your car sees redline/day: 15 track days/year.


broke throttle shaft 1 month after bumping rev limit to 7400. new chicken limit is 7000, don't need to go through that again.
I'm assuming everyone going past 7200 is running skunk throttle bodies?

Last edited by endura; 01-27-2015 at 04:46 PM. Reason: more info.
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Old 01-27-2015, 05:08 PM   #7
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Spinning stock head and cams to 8k = pointless.
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Old 01-27-2015, 05:09 PM   #8
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7500.

BP4W. BP5A ecu. I go hard.
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Old 01-27-2015, 05:23 PM   #9
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Quote:
Originally Posted by guttedmiata View Post
Spinning stock head and cams to 8k = pointless.
Not so. With a 7.5k revlimit I only get a 34mph wide powerband, spinning to 8.5k I get a 40mph wide powerband. I just run more and more boost the higher the revs get to keep the torque up.
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Old 01-27-2015, 05:34 PM   #10
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RPM Limit: 7400 hard, soft starts at 7200
Built engine: no, stock 90' 1.6
Engine Specs: whatever mazda says they should be
Track the car: yes, track only car
Avg number of times your car sees redline/day: 2-3 times per lap, 14 ish laps per session, 10 sesssions a track day= 280-420 times per track day(thats probably on the high end, 200-300 seems more appropriate)
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Old 01-27-2015, 05:55 PM   #11
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RPM Limit: 8200 soft 8350 hard

Built engine: Yes

Engine Specs: Scat rods, Supertech Pistons, Supertech valves 1mm over, Supertech 63lb dual springs, gates belt and WP, BE billet oil pump gears, balanced rotating assembly, stock flywheel, stock harmonic ballancer(for now), OEM head gasket, ARP hardware everywhere, ACL bearings. Turbo, 262hp last time on the dyno. MS3

Track the car: Nope, drag strip sometimes, daily drive in the summer sometimes.

Avg number of times your car sees redline/day: 5 maybe, a lot of times it's just downshifting. I see it most often drag racing as it is needed with the short gear ratio. I did one autocross and it came in handy then too but it wasn't there long.


Edit* Because Revlimiter: Beautiful gauges with 8200rpm redline.
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Old 01-27-2015, 05:56 PM   #12
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I am currently set at my desk. In about an hour I will be set in my NA.
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Old 01-27-2015, 06:22 PM   #13
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RPM Limit: soft-7000, hard-7200
Built engine: forged Crower rods, Supertech 8.4:1, Boundary pump
Engine Specs: NA8 head, heavily ported, stock valves, stock springs (this week;ST light doubles and titanium retainers waiting to go in), stock hyd lifters
Track the car: yes, please
Avg number of times your car sees redline/day: depends on the medication
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Old 01-27-2015, 06:41 PM   #14
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And a useful post.

7500 limit
Built: no
Engine: NB1 engine and head. Minor head porting. Stock everything. ~40,000 on this engine.
Track the car: once in a great while
Limit per day: Very often. It's not just a forum name.
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Old 01-27-2015, 08:51 PM   #15
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7k limit, soft at 6900, spark cut only
Built: No
Engine: 99, stock internals and head (i think), 154k miles
Track: 3 times last year while N/A, not yet since turbo
Rev limit per day: a handful
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Old 01-27-2015, 09:03 PM   #16
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rev limit: 7200.

Built bottom end (Carillo A-beams, supertechs), ported & polished head, oversized valves, stock cams, stock valve springs.

Why the 7200 limit? No point in going higher than that with the stock cams, and i like reliability. Of course, even with that it broke a throttle body screw at Laguna last September.

--Ian
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Old 01-27-2015, 11:39 PM   #17
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Wow, you guys are all fairly conservative.

My turbo car: 7200/7400, but it rarely goes to normal rev limiter

My n/a car: 7400/7500, multiple launches on the 2-step, usually shifted when power falls off but has been held on the limiter in autocross

Autocross and road race guys with standard valve components usually ask for 7500. I've seen/heard of a couple broken throttle shafts, but no reports of valve or rod issues. One of our guys has a "stock" 01 we set at 7500 soft, 7700 hard years ago. Had one issue where the cam trigger ring rotated--I can't believe it's just a friction fit (?!) from the factory. I believe he put a couple small tack welds on it after realigning it.

Built heads: 7500+ but up to the owner. SUB and custom cams 8000+. The guys who build those kinds of motors generally do not allow me to disclose any real info about them.
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Old 01-27-2015, 11:56 PM   #18
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Quote:
Originally Posted by Leafy View Post
Not so. With a 7.5k revlimit I only get a 34mph wide powerband, spinning to 8.5k I get a 40mph wide powerband. I just run more and more boost the higher the revs get to keep the torque up.
Ok, well I would agree if it keeps you from shifting, it MAY be beneficial. Not sure that widens your powerband exactly.
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Old 01-28-2015, 12:06 AM   #19
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Stock internals, the usual bolt ons, BP5A cam. Redline has been stock until recently, now now that I've gone MS it is set to 7500rpm. It sees redline almost every shift. Averaging about 35-40 days on track a year.

robert
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Old 01-28-2015, 12:59 AM   #20
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Interested in this thread. I'll be keeping my stock BP head for the time being so I'm curious what everyone else is running on stock heads. Looks like 7000/7200ish so far.
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