SR throttle response at low rpm's

[micahjan]

I have just finished an srswap and love the power when the turbo kicks in, but this motor has way less power than my stock ka before the turbo hits. Please let me know if this is normal, or if I still have some bugs to work out.

thanks

[ItzGenX]

What you are feeling is turbo lag and low torque/compression. You have a low compression motor which means less N/A power to begin with. Also, you have restrictive piping. The air that comes into the engine must travel through a lot of pipes to get into the intake manifold. Also, the exhaust must travel through an exhaust turbine forcing its way out robbing more power. What you feel is normal.

[implict]

why is that normal????? slow then fast.... hmmmm i dunno... need daunts info on this one

[91-240]

The sr20 has a lower c/r than a ka because of the turbo..Most if not all N/A cars have a higher c/r than forced induction cars which increases horsepower and torque.Using a higher c/r i.e. 9:1 or 9.5:1 would give you better off boost acceleration and possibly less lag but then you could run into detonation.Using a lower c/r in factory turbo cars increases the margin of safety but the trade-off is more lag...Its all what comes with a turbo motor...How do you like the sr20det? Im hoping to get my motor set from Daunt this spring or summer.

[ItzGenX]

Well picked up and explained 91-240. Thanks for the backup

[I H8 UR DSM]

why is that normal????? slow then fast.... hmmmm i dunno... need daunts info on this one

:thumbd

[Dori Dori]

Actually, it's boost threshold; not turbo lag.

micahjan, get a free flowing exhaust/downpipe and you will build boost quicker. Also, in some cases a boost controller can assist as well.

This is good info for some of you turbo n00bs, especially the KA guys looking to go to a SR. A turbo gives good power and torque, but comes with a price. Boost threshold and turbo lag. Also the SR has less displacement and a lower compression ratio, which gives the engine no low end grunt. A lot of Subaru guys that traded in their 2.5rs's (for those that don't know, it's a 2.5 ltr 4cly w/ similar power/tourque characteristics of the KA, version of the Impreza) for WRX's were very unhappy with the lack of low end power. They didn't do their homework. A WRX is a 2.0ltr like the SR, but has an even lower compression ratio...8.0/1. The car feels like it has maybe 40-50hp or just really, really bad gearing before the turbo builds boost. If that doesn't sound appealing to some of you, and you've been pipe dreaming about about a SR swap and a bigger turbo, think about this as well. Generally, the bigger the turbo the worse the lag and spool up are.

[micahjan]

Thanks for the input.

Dori Dori, my exhaust is as free flowing as they get, 3" no cat and only installed half way down right now. But a boost controller is coming soon.

As a "noob" I was definatly not ready for the lack of power before boost, but not ready for the power after boost either. I am still only running stock boost and love it. To me it feels like a two stroke bike when it hits its power curve. I am running the stock turbo with no plans to change it, but a very large intercooler, because I want to run 12 lbs reliably. I think I want to get the turbo xs dual boost controller, I have seen them on ebay for $175 ish, does anyone have any experience with them.

thanks

[I H8 UR DSM]

stock boost is slow, just wait till u run 12-14psi : )

you'll be happy.

i have the regular turbo xs boost controller, its fine..nothing too special, but does the job...we also sell both the controllers.

http://www.rollhard.com

[Dori Dori]

An MBC will do the job, but I would say to save your dough for an EBC. You run a higher risk of high EGT's and occasional boost spikes with an MBC than you would with an EBC. If you're set on an MBC though, save your money and build your own. It'll cost you around $5-$10 in parts and works just as well. Search around on the net for instructions on homemade mbc's.

[implict]

Well picked up and explained 91-240. Thanks for the backup

?????

[Dori Dori]

91-240 = Screen name of user that reiterated on ItzGenX's explanation that you doubted being true.

:thinker :rolleyes

[implict]

didnt doubt him at all.... just asked for daunts opinion.

[SRdS14]

slow then fast?? lol. i mean....after all it is turbo spoolin up

~Scott

[fenrisx]

whats the lag like on the CA18's

[george]

why is that normal????? slow then fast.... hmmmm i dunno... need daunts info on this one

dude its a turbo chargered vehicle...of course its normal. that what turbo lag is. try driving a supra with a T88. a description, full throttle....nothing...nothing....nothing ....nothing... oh shiit bye bye suprcharged mustang

[implict]

I have just finished an srswap and love the power when the turbo kicks in, but this motor has way less power than my stock ka before the turbo hits. Please let me know if this is normal, or if I still have some bugs to work out.

thanks

i didnt mean it liek that... he said the sr20 is slower than the ka.... before the turbo kicks in... i just dont understand that..... :uzi

[Daunttless]

Do you understand it now? If not, Less Displacement + Lower Compression = Less Offboost Horsepower and Torque. : ) I think Corky Bell's quote was ( since it appears Dori Dori has read Maximum Boost ) if there is no lag, you don't have a turbo. : )

[91-240]

Exactly Daunt.I love that book....Anyone who has a turbo car should get that book...

[Dori Dori]

Werd. Maximum Boost is a great book...sometimes it's a little boring to read and too technical for your average joe, but if you own a turbo'd vehicle or are thinking of owning a turbo'd vehicle, read it. It should be your bible.

[implict]

whats the name of the book?

[ItzGenX]

Maximum Boost :thinker :rolleyes

[Dori Dori]

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