Miatapower List Archive

This read-only message was archived from a public mail list.
Mail From: (email redacted)


Hi guys,

Pls. see my update and condensed turbo saga report on

fortunecity.com/marina/pontoon/3/miata/turbodynoruns/turbosummary.htm
l

In case the 9psi graph is missing:
fortunecity.com/marina/pontoon/3/miata/turbodynoruns/_9psisrn.gif

Am now running 9 psi (at least experimentally) :-)

Power is substantially better than when I first installed the turbo, but my
biggest beef is the spoolup is a bit slow and the boost threshold a bit high.
In 2nd gear I only reach 6 psi by something like 4000 rpm and 9 psi by something
like 4500 rpm. In 4th gear I reach 6 psi at 3700 rpm. I'd really like to
improve the 3k to 4k range.

What tends to be effective for improving spoolup? :

- Bigger downpipe (mine's stock Greddy),

- Bigger exhaust (mine's 2-inch with only straight-thru mufflers and no cat)

- Bigger intercooler (mine's tiny - 1 to 1.5 psi drop near redline at 6 psi
(manifold), and 55 deg C outlet temp on long WOT runs @6psi @30degC ambient).

- Earlier opening exhaust cam (mine's the auto tranny cams, what if I put in the
manual cams but advanced 1 tooth?) - this is supposed to provide more exhaust
energy to spin the turbo.


And what's the consensus on placing an old, say 50k mile exhaust cam into my
engine which is 13k miles, without changing the lifters?

Cheers,
Jason

This read-only message was archived from a public mail list.
Mail From: (email redacted)


In a message dated 1/27/00 6:24:29 AM Eastern Standard Time,
(email redacted) writes:

<<
- Bigger exhaust (mine's 2-inch with only straight-thru mufflers and no cat)
>>

Here's your problem.

Gibb

This read-only message was archived from a public mail list.
Mail From: (email redacted)





Of your current set up - I would think the 2 inch diameter exhaust would be the
limiting factor in flow. A 2 inch ID would give a flow area of 12.5 inches - a
2.5 inch ID increases that to 19.625 inches.

However - removing the cat from the stock system probably decreases pressure
drop the most, next would be replacing the muffler with a straight thru - which
is what you have already done.

Is your current 2 inch piping mandrel bent - or closer to the stock jagged
construction? Those angles might be part of the culprit on your pressure loss.

Dan




(email redacted) on 01/27/2000 08:02:01 AM

Please respond to (email redacted)

To: (email redacted), (email redacted)
cc: (bcc: Dan W Thorpe/WLGORE)
Subject: Re: slow spoolup





In a message dated 1/27/00 6:24:29 AM Eastern Standard Time,
(email redacted) writes:

<<
- Bigger exhaust (mine's 2-inch with only straight-thru mufflers and no cat)
>>

Here's your problem.

Gibb

This read-only message was archived from a public mail list.
Mail From: "Mel Hoagland" <(email redacted)>


Jason,

Based on my experience I believe the primary block in your way is exhaust
restriction. I have 2 1/2" all the way, with a free-flow cat in place. No
muffler. My turbo spins VERY quickly (pun intended).

Mel
------------------------------------------------------------
Mel Hoagland ((email redacted))
"Wheezy" black 96 FMII vrrooommmm


-----Original Message-----
From: (email redacted) <(email redacted)>
To: (email redacted) <(email redacted)>
Date: Thursday, January 27, 2000 6:40 AM
Subject: slow spoolup


>
>Hi guys,
>
>Pls. see my update and condensed turbo saga report on
>
>fortunecity.com/marina/pontoon/3/miata/turbodynoruns/turbosummar
y.htm
>l
>
>In case the 9psi graph is missing:
>fortunecity.com/marina/pontoon/3/miata/turbodynoruns/_9psisrn.gi
f
>
>Am now running 9 psi (at least experimentally) :-)
>
>Power is substantially better than when I first installed the turbo, but my
>biggest beef is the spoolup is a bit slow and the boost threshold a bit
high.
>In 2nd gear I only reach 6 psi by something like 4000 rpm and 9 psi by
something
>like 4500 rpm. In 4th gear I reach 6 psi at 3700 rpm. I'd really like to
>improve the 3k to 4k range.
>
>What tends to be effective for improving spoolup? :
>
>- Bigger downpipe (mine's stock Greddy),
>
>- Bigger exhaust (mine's 2-inch with only straight-thru mufflers and no
cat)
>
>- Bigger intercooler (mine's tiny - 1 to 1.5 psi drop near redline at 6 psi
>(manifold), and 55 deg C outlet temp on long WOT runs @6psi @30degC
ambient).
>
>- Earlier opening exhaust cam (mine's the auto tranny cams, what if I put
in the
>manual cams but advanced 1 tooth?) - this is supposed to provide more
exhaust
>energy to spin the turbo.
>
>
>And what's the consensus on placing an old, say 50k mile exhaust cam into
my
>engine which is 13k miles, without changing the lifters?
>
>Cheers,
>Jason
>

This read-only message was archived from a public mail list.
Mail From: (email redacted)



Jason...

If you change the cam... change the lifters!

Mark

>
> And what's the consensus on placing an old, say 50k mile exhaust cam into my
> engine which is 13k miles, without changing the lifters?
>
> Cheers,
> Jason
>

This read-only message was archived from a public mail list.
Mail From: "Steven Searle" <(email redacted)>


Jason, my 1.6 Greddy runs at about 12 psi, achieving full boost before 3250
rpm. Essential to this type of spool-up is a bigger downpipe (the stock one
is really restrictive); a 2.5 inch exhaust (Walker Dynomax muffler, IIRC);
no cat; and most importantly, a big, non-restrictive intercooler. Mine is a
Spearco unit, and is about 80% efficient (at about 10 mph), and loses less
than a pound of boost at red-line.

It could be that the higher compression ratio of my NA engine helps spool-up
as well, due to higher exhaust energy.

FWIW,
Steven Searle


----- Original Message -----
From: <(email redacted)>
To: <(email redacted)>
Sent: Thursday, January 27, 2000 4:20 AM
Subject: slow spoolup


> What tends to be effective for improving spoolup? :
>
> - Bigger downpipe (mine's stock Greddy),
>
> - Bigger exhaust (mine's 2-inch with only straight-thru mufflers and no
cat)
>
> - Bigger intercooler (mine's tiny - 1 to 1.5 psi drop near redline at 6
psi
> (manifold), and 55 deg C outlet temp on long WOT runs @6psi @30degC
ambient).
>
> - Earlier opening exhaust cam (mine's the auto tranny cams, what if I put
in the
> manual cams but advanced 1 tooth?) - this is supposed to provide more
exhaust
> energy to spin the turbo.
>
>
> And what's the consensus on placing an old, say 50k mile exhaust cam into
my
> engine which is 13k miles, without changing the lifters?
>
> Cheers,
> Jason
>

This read-only message was archived from a public mail list.
Mail From: Beau Randall <(email redacted)>


Someone on the Miataforum site said replacing the downpipe improved
spool by 500rpm... my bet is that is the biggest restriction. - Beau

--- (email redacted) wrote:
>
> Hi guys,
>
> Pls. see my update and condensed turbo saga report on
>
> fortunecity.com/marina/pontoon/3/miata/turbodynoruns/turbosummary.htm
> l
>
> In case the 9psi graph is missing:
> fortunecity.com/marina/pontoon/3/miata/turbodynoruns/_9psisrn.gif
>
> Am now running 9 psi (at least experimentally) :-)
>
> Power is substantially better than when I first installed the turbo, but my
> biggest beef is the spoolup is a bit slow and the boost threshold a bit high.
> In 2nd gear I only reach 6 psi by something like 4000 rpm and 9 psi by something
> like 4500 rpm. In 4th gear I reach 6 psi at 3700 rpm. I'd really like to
> improve the 3k to 4k range.
>
> What tends to be effective for improving spoolup? :
>
> - Bigger downpipe (mine's stock Greddy),
>
> - Bigger exhaust (mine's 2-inch with only straight-thru mufflers and no cat)
>
> - Bigger intercooler (mine's tiny - 1 to 1.5 psi drop near redline at 6 psi
> (manifold), and 55 deg C outlet temp on long WOT runs @6psi @30degC ambient).
>
> - Earlier opening exhaust cam (mine's the auto tranny cams, what if I put in the
> manual cams but advanced 1 tooth?) - this is supposed to provide more exhaust
> energy to spin the turbo.
>
>
> And what's the consensus on placing an old, say 50k mile exhaust cam into my
> engine which is 13k miles, without changing the lifters?
>
> Cheers,
> Jason
>
>
__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
im.yahoo.com

This read-only message was archived from a public mail list.
Mail From: (email redacted)


Dan wrote:

>> Is your current 2 inch piping mandrel bent - or closer to the stock jagged
construction? Those angles might be part of the culprit on your pressure loss.

I got a chance to examine it again, my exhaust is pretty kinky. I guess it
should be next on my list.

Thanks to all for your suggestions,
Jason

This read-only message was archived from a public mail list.
Mail From: (email redacted)


In a message dated 00-01-30 04:17:55 EST, (email redacted) writes:

<<
>> Is your current 2 inch piping mandrel bent - or closer to the stock jagged
construction? Those angles might be part of the culprit on your pressure
loss.

I got a chance to examine it again, my exhaust is pretty kinky. I guess it
should be next on my list.
>>

Is there a need for an exhaust gas backpressure check kit? Would be
easy/cheap, and would tell the whole story.
Corky

PS, working on the CRES water lines.

This read-only message was archived from a public mail list.
Mail From: "Malcolm Gray-Stephens" <(email redacted)>


>
> Is there a need for an exhaust gas backpressure check kit? Would be
> easy/cheap, and would tell the whole story.
> Corky
>
> PS, working on the CRES water lines.
>

.. just thinking about this today while trundling down the road (non Miata!)
... if we are to remove EGR from Link ... there is a nice little hole
left... could you get a temp gauge in there as well as a pressure point ...
or is a thermocouple on the outside of the manifold sufficent to get an idea
of temps... (I know... it is not measuring at source ... but what sort of
temperature gradient would you be looking at ..i.e. inaccuracy of using
surface mounted thermocouple)..

Malcolm G-S