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mhamrick · 05-12-2009, 11:33 PM

328FTW- You would have probably done better with a SC14 but a small turbo is fine too.

I agree with you to an extent on this topic.If he is worried about pulling off mid corner and does not want to break the rear end loose then yeah I agree. But he can have the same effect with a big snail also. Big turbos come on and come hard when they do. However a large turbo at 7psi can make as much as 100hp difference compared to a small turbo at the same psi. When racing this is a good thing because you will avoid heat soak in the Intercooler that a small turbo working its rear off will make. That is why you want to look at a compressor map and see where it efficiency islands are and find one that you are in its efficiency range in the RPM load you will most be using. This way you do not have a large expensive Hair dryer because you can turn a turbo into one very easily.

The other part where this is going to hurt is pulling on straights. The idea would be to keep the car in the boost (lets say the psi starts at 4k) and when exiting the turn be right in this area. A car with say a T3/T4 will rip a T3 out of a turn at the same RPM because you will be hitting the Big turbos efficiency where as the small turbo will be moving out of its efficiency. When driving a car on the track (paved of course) you would want to keep the car wound up anyway. Look at most NA cars and even those stay in the higher RPMs.

Basically when you build a turbo car you think of what you are going to be using the car for. If it is daily driving then you need to build it for the RPMs it will be used in. Most people drive their car in the 2k to 5k range. You would want a smallish turbo that starts boosting at 2k for this app. On a track car most of the time you are going to be in 4k and up. For that you will want to run a turbo that is spooling at 4k and running max by 5k but still in its efficiency range at redline.

If you build a turbo track car with a small turbo you are going to get outrun by a car identical but with a larger snail. However if it is on a track that is all turns then a small turbo may be better suited. However most tracks have more straightaways then turns. If you are going to use the car for both street and track then you will want to split the difference between a big and small turbo. A super 60 will put you in a good spot for not to much lag and still pull good at the top end.

Hope this helps..................

05-12-2009, 11:33 PM	#10 (permalink)
mhamrick Some Skills Join Date: May 2009 Posts: 61 Thanks: 1 Thanked 3 Times in 3 Posts iTrader Rating: (1/100% )	328FTW- You would have probably done better with a SC14 but a small turbo is fine too. I agree with you to an extent on this topic.If he is worried about pulling off mid corner and does not want to break the rear end loose then yeah I agree. But he can have the same effect with a big snail also. Big turbos come on and come hard when they do. However a large turbo at 7psi can make as much as 100hp difference compared to a small turbo at the same psi. When racing this is a good thing because you will avoid heat soak in the Intercooler that a small turbo working its rear off will make. That is why you want to look at a compressor map and see where it efficiency islands are and find one that you are in its efficiency range in the RPM load you will most be using. This way you do not have a large expensive Hair dryer because you can turn a turbo into one very easily. The other part where this is going to hurt is pulling on straights. The idea would be to keep the car in the boost (lets say the psi starts at 4k) and when exiting the turn be right in this area. A car with say a T3/T4 will rip a T3 out of a turn at the same RPM because you will be hitting the Big turbos efficiency where as the small turbo will be moving out of its efficiency. When driving a car on the track (paved of course) you would want to keep the car wound up anyway. Look at most NA cars and even those stay in the higher RPMs. Basically when you build a turbo car you think of what you are going to be using the car for. If it is daily driving then you need to build it for the RPMs it will be used in. Most people drive their car in the 2k to 5k range. You would want a smallish turbo that starts boosting at 2k for this app. On a track car most of the time you are going to be in 4k and up. For that you will want to run a turbo that is spooling at 4k and running max by 5k but still in its efficiency range at redline. If you build a turbo track car with a small turbo you are going to get outrun by a car identical but with a larger snail. However if it is on a track that is all turns then a small turbo may be better suited. However most tracks have more straightaways then turns. If you are going to use the car for both street and track then you will want to split the difference between a big and small turbo. A super 60 will put you in a good spot for not to much lag and still pull good at the top end. Hope this helps..................