Hi,

question is the topic, as mentiond i looked at some dyno sheets and notices that the torque at the low end (<3000rpm) on most Turbo Cars are lower then on NA Cars with the same engine... sometimes difference is not very small and i want to ask if anyone knows why this is like this?

and what can we do to make low end torque better? (without rising the displacement)

Thanks
Malte.

 

Well there are a few reasons, but here are a couple:

1. Basic engine configuration between a motor built for NA vs. a motor built for boost (NA motor = >10:1CR, boost = <9:1).
2. The turbo itself presents an restriction in the exhaust much like a VERY restrictive muffler.

 

the reason is lower compression than an na motor, that and the turbo isnt prodcuing positive pressure. if oyu want low end buy a smaller turbo, get a small shot of nitrous to help spool the turbo or go back to na

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Seriph &raquo;</TD></TR><TR><TD CLASS="quote">Well there are a few reasons, but here are a couple:

1. Basic engine configuration between a motor built for NA vs. a motor built for boost (NA motor = &gt;10:1CR, boost = &lt;9:1).
2. The turbo itself presents an restriction in the exhaust much like a VERY restrictive muffler.</TD></TR></TABLE>

Thats was also what i have thought... i think the turbo makes more effect then compression ratio...

but is it safe to run a small (25hp) shot of nirtous at 2-3k rpm? i though i read somewhere that it is safe to activate nos only after 3k but that doesn't make sens for the torque problem.

Thanks
Malte.

 

yea you can run a small shot like that, i wouldnt use a fogger because of the whole nitrous backfire from puddling thing, but a direct port would work

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wantboost &raquo;</TD></TR><TR><TD CLASS="quote">yea you can run a small shot like that, i wouldnt use a fogger because of the whole nitrous backfire from puddling thing, but a direct port would work</TD></TR></TABLE>

So the Problem will be the backfire on fogger systems... on direct port systems this would be no problem - thanks for the information... i will think about it

Thanks
Malte.


Modified by mrx at 6:50 PM 8/8/2005

 

the direct port wont be a problem, as it cant really pool in the intake manifold when its installed on a downward sloping manifld runner