Is there anyway to determine a cars exact redline after it's been modded/hybrid'd?

 

can a dyno accurately display a motor's limit?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 8point6 &raquo;</TD></TR><TR><TD CLASS="quote">Is there anyway to determine a cars exact redline after it's been modded/hybrid'd?</TD></TR></TABLE>

yeah with a tach guage.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1993sir05 &raquo;</TD></TR><TR><TD CLASS="quote">

yeah with a tach guage. </TD></TR></TABLE>

WTF? I need to determine the redline FIRST. A tach only displays the revs; it doesn't accurately display an egine's redline.

You're saying if I put a fully built motor into a hatch with a stock cluster my redline would still be under 7k...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 8point6 &raquo;</TD></TR><TR><TD CLASS="quote">
You're saying if I put a fully built motor into a hatch with a stock cluster my redline would still be under 7k... </TD></TR></TABLE>

have you thought about using a tach that reads higher than 7,000 rpm

 

your cams will mostly determine you redline and a dyno of course

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 8point6 &raquo;</TD></TR><TR><TD CLASS="quote">

WTF? I need to determine the redline FIRST. A tach only displays the revs; it doesn't accurately display an egine's redline.

You're saying if I put a fully built motor into a hatch with a stock cluster my redline would still be under 7k... </TD></TR></TABLE>

well if you have to ask that, then you shouldnt even be putting a fully built motor in anything.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 8point6 &raquo;</TD></TR><TR><TD CLASS="quote">

WTF? I need to determine the redline FIRST. A tach only displays the revs; it doesn't accurately display an egine's redline.

You're saying if I put a fully built motor into a hatch with a stock cluster my redline would still be under 7k... </TD></TR></TABLE>

Guys, this was sarcasm aimed toward the previous poster. I should've stated that.

 

your valve springs and valves(weight of them) determine your rpm limit. contact your valve spring manufacturer and they will be able to tell you.. you'll be able to get more rpm than they tell you if you have titaniium valves. however if you are asking this question than i am assuming you haven't sprung the 1600 dollars for titanium valves..stock springs & valves=stock rpm limit

 

what engine do you have? and is that engine stock?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v4lu3s &raquo;</TD></TR><TR><TD CLASS="quote">what engine do you have? and is that engine stock?</TD></TR></TABLE>

Any engine in general. I just wanted to know what the determining factor would be when finding a redline.

 

thats too general a question.

the first factor is WHAT ENGINE IT IS.

for example if you take an h22a with a 7200 rpm redline out of a prelude and put it in an accord or civic....guess what the redline is?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v4lu3s &raquo;</TD></TR><TR><TD CLASS="quote">thats too general a question.

the first factor is WHAT ENGINE IT IS.

for example if you take an h22a with a 7200 rpm redline out of a prelude and put it in an accord or civic....guess what the redline is?</TD></TR></TABLE>

You're missing the point of the question! All I needed to know was when an engine was built, (by Honda or a drag racer), how did they determine the motor's redline. Meaning: what device, if any, did they use to measure the strain on the motor and how were the results displayed?

When I build a motor someday, how will I find out how high I can safely rev it?

 

Here's a general response.The dyno will give you an idea of how high the engine makes power.No sense turning it 10k if it stops making power after 8k.The other factor is the mechanical limits of the parts.Connecting rod strength,piston speed,valve spring strength,and general weight of parts.
Glenn

 

Well this is going to sound like I'm a smart ***, but here goes;

Without being able to run finite element stress analysis on all the components, all you can do is build several similar engines and run them on an engine dyno until they break. Then average the RPM's that failure occured.

In one of the prior posts, comments were made about the valve assembly limiting it and that's also true. You could run an engine on a dyno and try to sense for valve float. Hopefully, you can shut down the engine prior to kissing a piston. Just adding a better valve assembly will not keep the rods or bearings from letting go at some RPM.

I think that you have to think about two different things;

When a factory first designs an engine, they do all the high dollar stress analysis on all the parts. Then build sample engines and do durability testing on them. The RPM limit that the manufacture sets is based on an exceptable failure rate.

When a drag racing group starts modifying an engine type, it's all trial and error based on what they have done in the past. Build an engine, make it fail, and then re-engineer the item that failed.

Wes

 

Thanks guys.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NJIN BUILDR &raquo;</TD></TR><TR><TD CLASS="quote">Here's a general response.The dyno will give you an idea of how high the engine makes power.No sense turning it 10k if it stops making power after 8k.The other factor is the mechanical limits of the parts.Connecting rod strength,piston speed,valve spring strength,and general weight of parts.
Glenn</TD></TR></TABLE>

i love all the **** people gave you to get a straight answer... haters

 

i lvoe stupid generalized questiosn that are not asking specificlaly what the poster wants to know.

specifcially stating "i would like to know how an engine manufacturer arrives at teh redline, and rpm rev limit" is a LOT better than asking what was asked.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 8point6 &raquo;</TD></TR><TR><TD CLASS="quote">Any engine in general. I just wanted to know what the determining factor would be when finding a redline.</TD></TR></TABLE>
Here's another factor. Any 'normal' cam profile will lose power at higher rpms. A car-company has to choose a cam that is acceptable at idle & during all the 'normal' driving that most customers do. That cam will leave power dropping off at high revs. The same sort of thing happens as a result of how well (or not) the head breathes.

So somewhere there's a speed at which it's pointless to rev higher, since you don't get more power by revving higher. Then they can design the rest of the engine to comfortably survive at that rpm.

Now since you originally asked about modded/hybrid engines, you can either hire a team of engineers to run FEA, or you can buy several engines & test them to destruction. But get videos for our amusement.