I was recently reading one of my older issues of Hot Rod (January 2001), when I came across an article on intake manifolds. It was talking about "tuned intake systems" and how they work. My question is that the tuning only works in a very narrow RPM range. Does anyone know what this RPM range is for a stock TPI? Is there a formula based on cam specs and intake runner length to determine this? I am swapping my TPI to an older car for a daily driver and it would seem to me that gas mileage would be really good in that RPM range due to the extremely high percentage of volumetric efficiency. Is my line of thinking wrong here? Anyway, if anyone can shed some light on the subject, I would really appreciate it. Thanks guys!

 

RPM range max is like 4,500-5,500 stock, not exactly sure though.

------------------
89 RS

STILL Looking For:
87 IROC-Z28 350 TPI

 

The article also stated that this tuning occurred in the low RPM. Are you sure that is right?

 

Notice he said MAX.
The MAX has nothing to do w/ the tuning. Also, just because your original TPI setup was set for band X, doesnt mean that it still is. By that l mean, carbon deposits, etc on the inside surface can changed that.

Clayton

 

tpi engines benefit from the tuned runner design(based solely on tourqe i believe)the reason for that is that it's easier to minipulate the velocity of the air fuel charge and burn rates at a lower rpm than at say 6000 the tuned design works as a supercharger per say(firing on two pulses).let's say when the #1 intake valve closes the engine goes into the compression stroke any air left in the plenum and runners bounces off the valve and reverts back through the intake again interacting with another cylinder's intake stroke when the number 1 intake valve opens again it has a ramming effect pushing more air into the combustion chamber at a higher velocity.the best analogy is an engine is nothing more than an air pump the more air you can get into it at a given time the more power can be made the tpi unit does this well except it has a price tag the long runner length hinders hp because you can't get those two pulses to travel fast enough to feed the engine at a higher rpm,that's where turbos come into play under pressure the intake design has less of an impact on power than the amount of volume the intake can support.

------------------
87 trans am,gm crate 350(4 bolt mains 10to1),L98 aluminum heads,LT4 hot cam,slp runners,slp 1 5/8 headers,3in.y-pipe,edelbrock base,hi flo cat,air foil,afpr,as&m ported plenum,gutted airbox,t-5 tranny w/centerforce clutch and a 3.27 9bolt(11.9in. brakes),ed wright's fastchip,relocated iat sensor,160 fan switch,tb bypass,accel supercoil,cap& rotor,hollowed maf,slp 3in. catbcak.

FOR SALE!FOR SALE!FOR SALE!FOR SALE!FOR SALE!

EVRYTHING IS FOR SALE WITH MY CAR (EXTRA ENGINE,TPI INTAKES,RUNNNERS,PLENUMS,ECM W/CHIP,ETC.
GETTING OUT OF THE 3RD GEN MARKET BEST OFFERS
CONSIDERED!!!!!!!!!!!