Quicker spool up

[pboglio]

I said the Intake does not control spool up, NOT exactly true. The turbine side controls the spoolup speed UNTIL you hit the surge line on the COMPRESSOR side, then you get no more. You can theoretically determine your MAXIMUM spool up possible by doing the following. Look at the surge line on a compressor map and find the pressure ratio and convert it to psi, then drop down vertically and look at the CFM or engine mass flow rate. Listed here is what I see off my map (Garrett 62 trim 60mm):

5 psi = 1.34 PR= 70,000 rpm = 120 cfm = 8 lb/min engine airflow
20 psi = 2.36 PR = 150,000 rpm = 240 cfm = 16 lb/min engine airflow

Now I've measured on my car using DSMLINK, going WOT at 2000 rpm I get the following airflow data:

2000 rpm = 5.8 lb/min = 0 psi boost pressure
2400 rpm = 6.2 lb/min = 0 psi boost pressure
2600 rpm = 8.7 lb/min = 5 psi boost pressure
2964 rpm = 14.4 lb/min = 15 psi boost pressure
3100 rpm = 16.5 lb/min = 20 psi boost pressure

You can see from my measured DATALOGS, I don't get 5psi until 8.7 lb/min. This is almost EXACTLY what the compressor map PREDICTS. I'm spooling so fast now that I'm on the surge limit the whole way thru, going to a smaller A/R wouldn't help me. I could feel the whole car vibrating until I got up to full boost. My datalogs show this. It shows up as a small rapid oscillation in rpm and airflow all the way until I hit maximum boost. I need to add mods that can make a big difference in engine mass air flow at LOW engine speeds BEFORE the turbo comes on boost, this is VERY difficult to do without resorting to nitrous, stroker kit, or high compression. Cheers.

 

[flinguist]

A GM MAF is supposed to help spool up times. I believe most people that have them use a 3" one, although they do have bigger ones.

 

[pboglio]

A GM MAF is supposed to help spool up times. I believe most people that have them use a 3" one, although they do have bigger ones.

I hear you. I've read other people that ran a 3" MAF and were raving about the spool up differences. Then I said what the hell and tried it for myself. Went and installed a VPC with NO MAF, better than any 3" MAF setup as far as intake restrictions are concerned. Didn't drop my spool rpm one bit. If you think about it how could it. The MAF is only a restriction during high flow rates, the engine flow rate during spool up is next to nothing, 5-10 lbs/min. Only thing that worked for me was eliminating EVERY single intake leak, including that damned leaking 1g CBV, and clamping the wastegate so tight you'd need 45 psi of exhaust backpressure to open it. These are the only things that helped to physically lower my spool up rpm.

 

[sweet97]

Spool related to exhaust pipes. Does a full 3" spool better than a 2.5" downpipe that opens to a 3" after the "test" pipe? Why to either answer!! Mark

 

[pboglio]

Mark,

Hows it goin. Spoolup happens when your car is bairly flowing any air at all, see my post above. This is when exhaust systems have a lot of flow capacity still left in them. Look at Buschurs Tech forum for the EVO. He dynoed a full 3" turboback vs. a 2.5" downpipe/3" catback setup. He stated that spool up was identical, horsepower was 1-2 h.p. less than a full 3" system. This was on an EVO knocking out about 316 w.h.p.

I saw little to no spool up difference going from a 2.5" catback to 3" catback myself. The car just "squats" harder once it does come on boost in 1st, 2nd, 3rd gears. Torque hits much more abruptly, almost like a small hit of nitrous. This is the advantage of less backpressure, not so much spoolup. With the 60-1 turbo your buying, I'd go full 3" all the way. For me, 2.5" downpipe to 3" catback on my little T28 works out just fine backpressure wise.

 

[sweet97]

Gene I am a ittle confused. If the 2.5" and 3" made almost no HP difference what will a 3" do for the 60-1?
There is a tuners guy ANCONOVER who can make a 3" for me but i know nothing of him. He gave me a price of around $650. for a 3" turboback with 4"x22" resonator and a Magnaflow I likwe with a big body, 5"x8"x18". Sounds llike it would be quite quet and still flo well. mark

 

[pboglio]

Ah, because Buchurs EVO was flowing 316 w.h.p. or say 38-40 lb/min . Your 60-1 turbo is capable of 60 lb/min or 600 horsepower. Big difference in backpressure once those airflow values are reached. Exhaust backpressure and compressor flowrate are directly related.

I would ask for pics of this guys exhaust work. $650 is reasonable for a turboback if its full stainless. That Magnaflow muffler is about 500 cubic inches in volume, pretty good. The resonator adds another 121 cubic inches. So the total volume is 621 cubic inches. This is more volume than the stock Thermal R&D (518 in3) or the Apexi (508 in3). Should be quiet enough. The thing I like about Thermal is they use 16 gauge tubing, kinda keeps things a little quieter. Some guys use 18 gauge to save a little weight, I don't like this thin gauge stuff at all.

 

[dsm-onster]

Sorry to bring this back from the dead. But this is very interesting to me. Pboglio, Do you remember what your peak airflow was with your small 16g with the 7cm^2 housing? and do you remember the airflow after the 6cm^2 housing was installed?

. . . I'm wondering if a clip and a 6cm^2 turbine housing flows enough for pushing the small 16g to its limits. And I wonder if a 10* clipped td05h turbine and a 6cm^2 housing spools faster than an unclipped td05h turbine and a 7cm^2 housing. . .

 

[JusMX141]

This is an interesting post....mostly because when I sell a Small 16G to a customer and their car is an Auto, they get a ported 6cm2 housing rather than the 7cm2 housing for this very reason.

I'd love to know before / after airflow numbers too!

 

[dsm-onster]

Hopefully your customer doesn't use the stock automatic exhaust manifold. The bore of the outlet is much smaller and OFFSET to a td05h turbine inlet .

 

[JusMX141]

I make sure they're not using the 5cm2-offset manifold before I ever send them a 16G.

A 2G manifold with the lip removed mated to a 6cm2 housing with the lip removed as well is the hot item for a Small 16G / Auto DSM upgrade; as long as they're not planning on running insane boost levels.

 

[dsm-onster]

Yea, it seams the small 16g is the best upgrade turbo for stock stall. My brother is debating running the 14b with the 2g manifold or the small 16g. I was wondering about clipping the 16g and using a smaler turbine housing: will you get faster spool and still flow well like the unclipped wheel in the 7cm^2 housing? . . . You are inadvertently lightening the turbine wheel with a clip, and the 6 cm^2 housing forces a tighter angle of incidence onto the turbine blades. Less energy is used, but flow potential goes up. A stock, "creepy" wastegate and a tight actuator spring will help insure a good spool. While when there needs to be more flow higher in the rev range, the clip allows the turbine to exhibit that higher flow potential . . . Just brainstorming. But, I think it's something to experiment. It may do nothing. It may be just swapping the devil for the witch.