How can I tell if my throttle body is to small?

For discussing injector selection,manifold modifications, throttle bodies, fuel supply system design and construction, and FIdle valves and IACs.
Forum rules
Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.

If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).

If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days

The full forum rules are here: Forum Rules, be sure to read them all regularly.
Post Reply
bmcewen
Helpful Squirter
Posts: 70
Joined: Tue Feb 22, 2011 3:17 pm
Location: northern colorado

How can I tell if my throttle body is to small?

Post by bmcewen »

I believe that I read somewhere that if you can hit the same MAP reading at full throttle that you have at Idle than your throttle body is not restictive. Is that true? What readings would be effected by throttle body sizing? FYI I am not looking for someone to tell me wether or not they believe that my throttle body is sized correctly.
1978 Camaro Lt 383 L98 HSR Th350(for now) 3:42s
MSII v3 main board rev2.891 8-pin HEI MSD BlasterII
COMP CAMS XR276HR
TRICKFLOW 23° 2.02/1.6
Full roller valvetrain, 11.1:1 compression
Bernard Fife
Master Squirter
Posts: 475
Joined: Thu Oct 29, 2009 12:54 pm

Re: How can I tell if my throttle body is to small?

Post by Bernard Fife »

bmcewen,

Ideally, for a NA engine your MAP reading at WOT will be the same as the baro reading at start-up. That indicates no restriction at all.

However, as long as the MAP doesn't decrease significantly (more than a couple of kPa or so) with the throttle wide open as you approach the RPM at which peak horsepower is made, you are good.

The MAP at idle doesn't come into it.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it.” - George Bernard Shaw
bmcewen
Helpful Squirter
Posts: 70
Joined: Tue Feb 22, 2011 3:17 pm
Location: northern colorado

Re: How can I tell if my throttle body is to small?

Post by bmcewen »

Yeah, I didn't mean to say idle. The reason I ask is I was expecting my stock 48mm throttle body off of a 94 camaro to be restrictive. Are the HP and torque numbers calculated by Mega logger wheel horsepower and torque?
1978 Camaro Lt 383 L98 HSR Th350(for now) 3:42s
MSII v3 main board rev2.891 8-pin HEI MSD BlasterII
COMP CAMS XR276HR
TRICKFLOW 23° 2.02/1.6
Full roller valvetrain, 11.1:1 compression
Post Reply