just curious as to how high i can get my rpms and what valvetrain mods/head mods would i need if i decided to tune in that direction?
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02-27-2010
just curious as to how high i can get my rpms and what valvetrain mods/head mods would i need if i decided to tune in that direction?
02-27-2010
High RPM's = no power for these motors. Keep them under 6200
02-28-2010
i see... good to know. thanks blue. so 6200 reachable with stock heads?Originally Posted by bluegtp91
02-28-2010
Not to bash but I have no idea how lower rpms would better more rpm more air more power i think thats pretty simple now what parts and tuning to mkae higher rpms with out things breaking is the real question.
02-28-2010
Theres also a limit to the usable RPM range of a specific engine.
You can change that, but consider what speed these engines reach their peak power at when stock.
02-28-2010
first off this is a very general question..... im guessing you have a gtp.... also are you stock cam'd?????
different cams can change the powerband along with different mods. but with that being said the stock cam peaks power around 5k. there is not much of a need in OVERreving the motor out of its powerband, there is no power, simple let it shift and contine to work.
stock springs are good for 6kish, ive seen 6600-6800 a few times with out a hick-up. but at the same time, i have headers, rockers, intake and pulley and i dont shift anything higher than 6k. i feel as if there is no power up there with the stock cam.
02-28-2010
yeah its stock cam but im planning on modding the cam and whatnot so idk
02-28-2010
on stock cam power will drop off anything past 5500 or so. its pretty weak.
if you went with a bigger cam then you can move the powerband up. with a cam on stock heads i wouldnt push it much farther than 6200 or so. if you had a big cam and headwork to match i would see 6800 max.
02-28-2010
You'd have to spend gobs of money to get our motors up by the 6800-7000 mark. If you go aftermarket cam an supporting valvetrain mods 6200-6400 isn't unreasonable.
03-01-2010
I look at it like this you dont see high rpm engines making the TQ a pushrod engine does however the TQ will sacrifice higher rpm very similar to a diesel, tons of TQ not very rpm happy. Almost every SOHC, or DOHC engine ive ever read about makes HP not TQ.
03-01-2010
fords 2 valve 4.6 OHC motor makes 260hp 320tq.
then here is a pushrod motor spining over 9k rpms.
http://www.fototime.com/ftweb/bin/ft.dll/detailfs?userid={1E8C76E5-FF0B-450B-831D-69C6B84CD161}&ndx=2&slideshow=0&AlbumId={AC298178-B1A4-493A-81B7-2E03933F8796}&GroupId={C8022D64-39FF-4D55-BA33-8008C3E0E8DC}&screenheight=800
there is ALOT of variables that determine how a motor spins and where it makes power.
03-01-2010
The 99-04 mod engines make 260hp but the 2005+ 3 valves make the 320 ft/lbs. I know it take a ton of other factors to make high rpm like stroke bore size ect.... I would dare say my old 95 GTP GP would spank my 02 GT GP stock for stock. I actually miss my 95 GTP more than the car I have now.
03-01-2010
my bad 04 is 260hp 305tq. 05 is 300hp 320tq. OHC's that make more TQ than HP.
bore and stroke is more so gonna equal torque. but you can have a big bore with a small stroke and turn some high rpms. high end hp is more so gonna come from heads, intake manifold, cam (that is set up for high rpm use)
03-02-2010
The mass of the rotating assembly also determines how freely it revs which affects how enjoyable or feasible high RPM's are.
03-02-2010
very true.
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