Sr20 stock bottom end - max rpm - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Silvi · 07-09-2017, 07:23 AM

Im building a 9k+ rpm head
How much RPM the bottom end(stock) internals can handle?

PoorMans180SX · 07-09-2017, 08:10 AM

What're you doing, going for some kind of record? Just keep it at 7500rpm, it's never going to make power past that anyway.
What cams?
What turbo?

Silvi · 07-09-2017, 02:58 PM

Tomei 270's
Im not looking for a record or crazy power output, just about 400-500 whp with wide rpm range

kyral · 07-09-2017, 03:04 PM

Id imagine it would hold up to 9k RPM's no problem. its fully counterweighted. and the heads the known weak point for revving that high anyway. so its not like an SR bottom end has never been taken to 9k before

PoorMans180SX · 07-09-2017, 05:03 PM

Quote:

Originally Posted by Silvi

Tomei 270's
Im not looking for a record or crazy power output, just about 400-500 whp with wide rpm range

You will make sharply declining power after 7500rpm if you aren't running a decently large turbo that can feed in extra boost.

Silvi · 07-10-2017, 02:06 AM

For now, until 7000 rpm its pretty stable - using stock head and 1.2 bar of boot with the current turbo (gt2871r)
http://oi57.tinypic.com/29y49wz.jpg

R@ddy · 07-10-2017, 02:24 AM

I'm assuming you're building a solid lifter head at the very least? Stock bottom end can be revved to about 8K rpm safely..and by safely I mean <400whp. Anything above that and you're pushing the limits of the stock rod bolts.

Silvi · 07-10-2017, 03:18 AM

yes, completely built head

hanzbrady · 07-10-2017, 06:33 AM

It'll go until it doesn't anymore and it'll be completely reliable until then.

High RPM = High Chances of Breaking Shit Quickly

My SR snapped an OEM rod at about 400hp and sent it through the side of the block and that was on the factory redline.

Kingtal0n · 07-10-2017, 08:21 PM

I'd say 7500max.

Tight stock bearings dont like to be spun high. LOTS of failed stock bottom ends out there making well below 400 horses. And I've had a few making 380 that lasted quite a long time with a 6500rpm rev limiter. IMO 7200+ Is pushing it too far. iirc, the FSM says the rod bearing can be as tight as 0.0008". Whereas you might want something like 0.002" instead for that much rpm.

07-09-2017, 07:23 AM	#1
Silvi Leaky Injector Join Date: Nov 2011 Location: IL Posts: 133 Trader Rating: (0) Feedback Score: 0 reviews	Sr20 stock bottom end - max rpm Im building a 9k+ rpm head How much RPM the bottom end(stock) internals can handle?

07-09-2017, 08:10 AM	#2
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 36 Posts: 5,574 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	What're you doing, going for some kind of record? Just keep it at 7500rpm, it's never going to make power past that anyway. What cams? What turbo? __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

07-10-2017, 06:33 AM	#9
hanzbrady Zilvia FREAK! Join Date: Apr 2015 Location: Floriduh Posts: 1,166 Trader Rating: (4) Feedback Score: 4 reviews	It'll go until it doesn't anymore and it'll be completely reliable until then. High RPM = High Chances of Breaking Shit Quickly My SR snapped an OEM rod at about 400hp and sent it through the side of the block and that was on the factory redline. __________________ [email protected]

07-09-2017, 02:58 PM	#3
Silvi Leaky Injector Join Date: Nov 2011 Location: IL Posts: 133 Trader Rating: (0) Feedback Score: 0 reviews	Tomei 270's Im not looking for a record or crazy power output, just about 400-500 whp with wide rpm range

07-09-2017, 03:04 PM	#4
kyral Zilvia Junkie Join Date: Nov 2012 Location: wisconsin Age: 32 Posts: 448 Trader Rating: (7) Rides Gallery: kyral Feedback Score: 7 reviews	Id imagine it would hold up to 9k RPM's no problem. its fully counterweighted. and the heads the known weak point for revving that high anyway. so its not like an SR bottom end has never been taken to 9k before

07-10-2017, 02:06 AM	#6
Silvi Leaky Injector Join Date: Nov 2011 Location: IL Posts: 133 Trader Rating: (0) Feedback Score: 0 reviews	For now, until 7000 rpm its pretty stable - using stock head and 1.2 bar of boot with the current turbo (gt2871r) http://oi57.tinypic.com/29y49wz.jpg

07-10-2017, 02:24 AM	#7
R@ddy Nissanaholic! Join Date: Jul 2008 Location: Zacatecas, Mx; Paramount, Ca Age: 34 Posts: 1,628 Trader Rating: (32) Feedback Score: 32 reviews	I'm assuming you're building a solid lifter head at the very least? Stock bottom end can be revved to about 8K rpm safely..and by safely I mean <400whp. Anything above that and you're pushing the limits of the stock rod bolts.

07-10-2017, 03:18 AM	#8
Silvi Leaky Injector Join Date: Nov 2011 Location: IL Posts: 133 Trader Rating: (0) Feedback Score: 0 reviews	yes, completely built head

07-10-2017, 08:21 PM	#10
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,829 Trader Rating: (17) Feedback Score: 17 reviews	I'd say 7500max. Tight stock bearings dont like to be spun high. LOTS of failed stock bottom ends out there making well below 400 horses. And I've had a few making 380 that lasted quite a long time with a 6500rpm rev limiter. IMO 7200+ Is pushing it too far. iirc, the FSM says the rod bearing can be as tight as 0.0008". Whereas you might want something like 0.002" instead for that much rpm.