Competition Going from PDR HX40 to PDR HX40 twins

[JLewis]

Hey guys, I'm considering upgrading to twins. Right now I have the PDR HX 40 and it just isn't supplying enough air. My truck is a 98 12 valve 5- speed with a #0 plate, 370's, 4k GSK and laser cut DV's and will smoke thick at full boost. My truck has a 4 inch lift with 35 inch tires so spool up I guess could possibly be an issue with twins with the HX 40. My question is for those of you that have gone from the PDR 40 to the PDR 40 twins, how is the spool up with the twins compared to the single and is there a big difference in top end with the twins? I figure I might as well use the 40 that I already have to keep the price down but don't want any more lag than I have now. I also tow around 8,000 lbs max during the summer, do these twins tow alright? Thanks Jim

 

[BPINE]

Hey Jim, I just got through with a set of PDR 40 twins on a truck that had a PDR 40 on it before. The spool up is a bit slower but not much and the top end is much better than before. Max temps with the 40 were 1600+ now under 1300. Boost with the 40 was 42 now 63, I still need to get that down a bit. The owner is going to tow but has not so far. This truck is an auto and there is no problem with spool up at all.



I have the 35 twins on my truck for towing but will put a 40 on it to see how it works in the future.



Blair

 

[JLewis]

Thanks Blair, did you ever have a PDR 40 on your truck? I'd be interested in how it compares to your HX 35 set of twins in terms of spool up and top end increase. Why do you want the boost down from 63 psi? Is the head on that truck not set up for that much boost or does Pier's not recommend that much boost? The temp decrease sounds great. Thanks for the reply. Jim

 

[BPINE]

Yes I had an HX-40 on my truck before and this twin system doesn't seem any slower to spool at all. Remember the manual trans truck are not quite as bad as the autos when it comes to spooling due to more gear selection.



Both mine and my buddies truck with the 40 twins have stock headgaskets with studs so I would like to keep them below 60 psi.

 

[Stomp]

First gen

I should have my First Gen pickup back next Saturday with the exact same combo. I was going to use a hybred 35/40, but after talking to a few different people I decided to go ahead and use my Piers HX40/16 combo. They way they put it you need proper breathing to get the best possible numbers. The problem is I have only a limited amount of fuel coming from the ve pump. So they also told me that I probably will lose some bottom end and somewhere around 1800 rpm's it is going to really take off. If I dont like it or if it doesnt work out all that great I will put a hybred on it later.



Stomp

 

[Snow man]

BPine,how are you going to keep boost below 60psi, without sliding the plate back. The PDR HX40 doesnt spool as fast in a twin system,the first 10psi come slower,once it hits about 10psi,it is the same as a single til about 20psi or so,from 20psi on up is insanely fast,almost instantaneous with your foot going down. it takes longer to get the first 5psi of boost than to go from 10-65psi+.

Stomp, if i were you id use the hybrid 40/35,you dont have the fuel to use a full 40 to its fullest,why not have the response of a tight hx35 exhaust housing if there will be no hp penalty. I also heard you say the best possible "numbers":. Hp numbers are important of your builiding a dyno truck,but if your going to drive this truck,trust me take 5hp loss on the very top end, for an average 15hp gain in midrange,lower egts in midrange,and way more bottom end power. Too mnay people get caught up in hp numbers,and not how the truck runs every day. THe pdr hx40 twins are awesome,I just think you dont have the fuel for them,and would be much happier with the pdr hx35 towing twins.

 

[BPonci]

My 40/3b spools great even in low power mode. When im at 6psi in the hat im building 1 psi in the cold pipe. I have tried 35/12, 35/14, 40/12, 40/14 and i now run a 40/16 and love it. I thought i might have a issue spooling the bottom end but i dont. I run 35 mudders ,3:55 and a 6 speed with no problems at all. If the system is set up right you should have no problem at all spooling them. Stomp has plenty of fuel and more coming.

 

[BPINE]

BPine,how are you going to keep boost below 60psi, without sliding the plate back. The PDR HX40 doesnt spool as fast in a twin system,the first 10psi come slower,once it hits about 10psi,it is the same as a single til about 20psi or so,from 20psi on up is insanely fast,almost instantaneous with your foot going down. it takes longer to get the first 5psi of boost than to go from 10-65psi+.

Stomp, if i were you id use the hybrid 40/35,you dont have the fuel to use a full 40 to its fullest,why not have the response of a tight hx35 exhaust housing if there will be no hp penalty. I also heard you say the best possible "numbers":. Hp numbers are important of your builiding a dyno truck,but if your going to drive this truck,trust me take 5hp loss on the very top end, for an average 15hp gain in midrange,lower egts in midrange,and way more bottom end power. Too mnay people get caught up in hp numbers,and not how the truck runs every day. THe pdr hx40 twins are awesome,I just think you dont have the fuel for them,and would be much happier with the pdr hx35 towing twins.

Snow Man I have mine set at 55 lbs with no problem you just need a big wastegate. I also agree with what you said it might be slightly slower the first few pounds to spool but once it starts it builds boost much faster. It is just hard to explain all this on this crazy keyboard!!!!

 

[JLewis]

Thanks guys, I've made up my mind to go with the 40-3B twins, will order on monday. I haven't done anything to my head yet, still trying to decide which gasket to go with the o-rings. I've heard the 3rd gen gaskets are holding up pretty well with studs and o-ring too I guess. I'll probably just get a brand new ported head already o-ringed. Hey Bponci have you run your rig on a dyno? Sounds like a strong set up!

 

[Stomp]

BPonci and I will be going to a dyno event on Jan 15 in Rohnert Park CA. He is the one Building my twins. He is doing an awsome job and I should have it back next Saturday. I will get to play with it for a while before the dyno day. Oo. Oo.



I will be having a new fuel pump built with some special parts hopefully before the dyno event. If not we will see what it will do with my already work over ve pump. It flows quite a bit. The 40/16 alone cant cleen it up.



Stomp

 

[**ICEMAN**]

i ran my pdrhx40/16 as a single for a good while and then used the same turbo in my 40/3B twins.

as a single i had it gated at 42 and now 25

no noticable difference in spool up.

once it hits 10lbs boost it will peg my 60lb gauge in a blink of an eye.

1600* at 2/3 throttle as a single

1250* at WOT now without water injection.

you should dyno before and after the twin install. i'd be curious to see your hp gain.

mine gained 78rwhp with the twin addition.

 

[Jim Fulmer]

A 400 degree drop in EGT's is about right going from a single to Twins using the same top turbo..... you might see a little more but it would be gravy. I noticed that same drop when I did that swap 2 years ago.



Jim

 

[Snow man]

I went fro ma large housing B1 with Bully dog 7s 1780 egts 485hp to PDT twins 1300 EGTS ,and 547RWHP

 

[Snow man]

I went from a large housing B1 with Bully dog 7s 1780 egts 485hp to PDR twins 1300 EGTS ,and 547RWHP

 

[Stomp]

I had mine on the rollers last July up at the first gen day at Piers. 419hp/1000tq on #2. I have done some more things to the fuel system and put a Stage 2+ oringed head on with 12mm studs/ats 3 piece manifold. I would like to see 500hp on #2. We will have to wait and see what it will do in January.



jlewis did you ever dyno yours with the HX40?



Stomp

 

[JLewis]

I haven't dynoed my truck at all yet. I'll see if I can set up an appointment before and after. I would like to see where I'm at now but before I dyno with the twins I'll have to do something about the head first