bigbadboy

what is the spool time on these. looking to start to grow on my project so i want to start to do some research before i get into anything. so my question is at around what RPM does the GT40R hit full boost and how many RPM's later will it take the 42R to hit full boost??

Justin Olson

The gt42R will spool around 1000rpm slower then the gt40R.

jpenman50

it depends if you have a divided collector... If so the 42 will make full boost, 35 psi, by 6000 k... I did the test myself... flat out amazing

a1320addict

iTrader: (1)

How's the transient response?

tony1

Night and day difference in transient response between the two. The 42r is for a car making 700+ where transient response isn't so much of a concern. The 40r could easily be a "street" turbo, but i wouldn't recommend the 42 for a street driven car. Transient response on the 42r with the right manifold setup is better than the non bb 72-74mm turbos with GTQ and up wheels.

Justin Olson

Tony1 on Ramonds car, what rpm are you getting 30psi at with the GT4294R and divided full race manifold ?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Night and day difference in transient response between the two. The 42r is for a car making 700+ where transient response isn't so much of a concern. The 40r could easily be a "street" turbo, but i wouldn't recommend the 42 for a street driven car. Transient response on the 42r with the right manifold setup is better than the non bb 72-74mm turbos with GTQ and up wheels. </TD></TR></TABLE>

tony1

I see 30psi by 6500, and about 5500 with the 40r.

jpenman50

I am willing to bet that it is around 6000 k.... It has everything to do with the divided collector.... I did a back to back test and it litterally spooled 1500 rpm faster and made 5 more psi (due to high shaft speeds at this altitude.) My setup went from making 31 psi @ 7500 rpm.. to making 36 psi@ 5800 rpm... (with bent valves)... the diff. is huge. we are talking almost 200 lbs/ tq. difference@ 5800 rpm...

a1320addict

iTrader: (1)

Tony, thanks for the information regarding the response characteristics. The 42r is way too big for a street car, I'm perfectly happy with my 30r, but I like knowing the 40r is there if I need it.

bigbadboy

jpenman50, do you have any pic of a divided collector?? i want to know what it looks like so when i go to get a top mount. i was thinking abt getting a 35R but i'm not sure if its gonna make the power i want.

Justin Olson

Here is a divided Topmount by Full-Race:



http://www.full-race.com/catal...=1038

bigbadboy

why does the divided spool faster than an undivided?? whats the secret

Justin Olson

It pairs the exhaust pulses to keep them from interfering with each other. The firing order of a honda is 1,3,4,2.

The drivers side of the divided volute pairs charges 1 and 4.

The passenger side of the divided volute pairs charges 2 and 3.

As you can see from the firing order,

The pulse from cylinder number 1 goes in the the drivers side of the divided volute,

Then the pulse from cylinder number 3 goes in the the passenger side of the divided volute,

Then the pulse from cylinder number 4 goes in the the drivers side of the divided volute,

And finally the pulse from cylinder number 3 goes in the the passenger side of the divided volute.

As you can see, one side of the divided volute gets a exhaust charge, then the other side of the divided volute gets an exhaust charge. By timing the exhaust pulses like this the turbine gets a steady stream of exhaust flow from the engine. Also, by dividing the cylinders into pairs of 2 that fire 360 degrees of crank rotation apart, you all but elimante cross contaminating cylinders. This means as cylinder 1's exhaust valves are open and the hot exhaust charge is traveling towards the turbine wheel, its pairs cylinder number 4's exhaust valves are closed as its on its compression stroke. This reduces reversion in to the combustion chamber. This makes more power by giving a cleaner combustion air charge, and also opens the door up to use long duration high lift cams.

Regards,
Justin

bigbadboy

thanks a lot. i appreciate it. i got it know. i thought u had to had a divided turbo housing to use a divided turbo manifold. but i guess u dont. what company besides full-race makes a good top mount with a divided collector

Justin Olson

You need to use the divided turbine housing with the divided manifold or your wont see any advantage over a normal exhaust manifold.

Regards,
Justin

DRIVENRacing

i just got my car on the dyno, i can say that the spool time of the 4088r impressed me, i cant wait till full boost

Kelly.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigbadboy &raquo;</TD></TR><TR><TD CLASS="quote">what company besides full-race makes a good top mount with a divided collector</TD></TR></TABLE>
Tim @ http://www.TurboElements.com

not sure if it listed on his site, but email him, i heard he is making them

cuin9sec

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Justin Olson &raquo;</TD></TR><TR><TD CLASS="quote">Here is a divided Topmount by Full-Race:



http://www.full-race.com/catal...=1038</TD></TR></TABLE>

same manifold i have...pure sickness!!! ilove full-race with a passion...lol! and i am in the process of buildinga gt42r setup....

it will be on the steets 2-3 days out of the week...

i dont care how late it spools ... once it does...hang on...lol!

Justin Olson

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigbadboy &raquo;</TD></TR><TR><TD CLASS="quote">thanks a lot. i appreciate it. i got it know. i thought u had to had a divided turbo housing to use a divided turbo manifold. but i guess u dont. what company besides full-race makes a good top mount with a divided collector</TD></TR></TABLE>

Dont forget Turbo Jesse(Arizona Forced Induction) and JG Fab. They both make divided topmounts!

JG Fab:
https://honda-tech.com/zero...age=1



Turbo Jesse:
https://honda-tech.com/zerothread/1664706

cuin9sec

not a bad topmount for the price!!

bigbadboy

sweet thanks for the help guys