Chriz88DX

iTrader: (1)

How will it spool slower if it moves more air? Also thanks every body for all the input

RotaryEvolution

iTrader: (30)

lower air velocity.

Chriz88DX

iTrader: (1)

Ok I just got a little confused so I have more air volume but less velocity it will spool slower but less volume and more velocity will spool quicker how is the so can some one explain?

RotaryEvolution

iTrader: (30)

smaller turbos for example use faster air velocity but push less overall air volume because they are smaller. smaller ports, exhaust, twin scroll holding half the exhaust passage closed, etc all are examples of higher velocity airflow which help the turbo react faster.

the larger you open up the airflow through the engine(bigger turbo, ports, intake piping and exhaust) the less velocity there is but more airflow capacity, meaning more peak horsepower but slower spooling of the turbo, same turbo on an engine with smaller intake diameter through the intake/exhaust tract will spool the turbo faster.

think of blowing through 2 straws, a stir straw will give you more restriction but the air going through should be moving at a faster pace but with less volume(noticed by the back pressure in your mouth). now take a large straw and blow through it, much less restriction and more air moving but the air moving through it is going slower. eventually you will choke the airflow to a maximum speed and just create a huge amount of backpressure with both if you tried to force enough air through each one.

joeylyrech

iTrader: (11)

A 60-1 with a 1.00 AR divided P-trim unit should be good.also look into at least a 40mm wastegate.

joeylyrech

iTrader: (11)

Karack that is something that i still dont understand,maybe you can help me out.When my car wasnt bridged(big streetport) with a 72mm turbo,1.00 AR divided p-trim i wasnt getting boost until like 450k to 500k rpms and then it will hold it steady until 9k.Now same motor with a big *** bridge with notched housings,f68 exhaust wheel,1.15 AR divided 76mm wheel will hit boost at 4k holding all the way up to 9-10k and if i wont get off the gas on top end it will keep building boost.So if the bridgeport moves air slower why boost is hitting lower on the rpm range with a bigger turbo than before?Granted is not a nice steady pull like it was when it was streetport is more like a switch but i am building boost faster than before,now my lower end sucks i have to drive keeping the rpms way up if i am in stop and go traffic.If i try to cruse at anything less than 3800rpms the car will bog,stall total pain in the *** but that might have to do with having a single blade t-body.

RotaryEvolution

iTrader: (30)

the only way to compare boost lag is with exactly the same setup before and after just the porting change. i can't say why yours is more responsive now than before. the boost should hit quicker but spool later in the RPM range, the gutless bottom end is to be expected, with the air velocity explanation.

Chriz88DX

iTrader: (1)

That makes sense thank you for explaining that.
As for joe I think it may be the single blade throttle body man or your port work may be too much my half bridge is only. Gutless under 2k it nice a 3k so it just seems that much slower between those two points but. But if my motor has get up at those points it should still have them if as long as I am not in boost right? Now this brings me to another ? Only running ten pounds what injector sizes will I need right now I am running 460 primarys and 550 secondarys and they are only at 30% at full load and my AF's are at steady 13.2

Also that's again every one for chiming in I can't say that this is helping me out alot

RotaryRocket88

iTrader: (7)

You're going to blow that engine if you're seeing 13.2 AFR with 10 lbs. of boost. You need to be running a LOT more injector than 460/550. That's not even what a stock TII has.

Aaron Cake

iTrader: (1)

Have not had much time on the forum lately so excuse my late response...

I'd have to disagree about bridgeports making turbos less responsive due to my own experience. I've set up two cars (mine and a friends) using the same turbo on both a bridged and unbridged engine. In both cases the result was dramatic.

My car with a small bridgeport would spool the stock HT-18 just off of idle like an on-off switch. Granted, at the same time I did change a bunch of stuff (intake manifold, intercooler and piping, etc. etc.) but it was fairly evident that the major factor was the porting. The turbo could be heard wooshing to the rhythm of the engine.

The 2nd car was a 1st gen turbo with a 13B and a T4B Chinacharger. The engine cracked a block due to water freezing, and when it was rebuilt it was bridgeported. That was the only change made and turbo response was about 1500 RPM better than the stock ported version.

The low RPM misfires induced by the overlap tend to create much higher combustion pressures every few cycled and this, combined with the bit of afterburn, really push a turbine.

All that said, no point running 300HP on a bridgeport. That's stock/mild street port territory. Putting a single blade throttle body on it will be even worse.

Chriz88DX

iTrader: (1)

Well I just want to get the build going you know I am only running a rtek (2.1 turbo) for now so I don't want to over do it but iam sure the boost bug will bite me and I will get something bigger lol so what injectors should I get?